Curative &amp; Method

ABSTRACT

A thermoset material containing β-hydroxyesters wherein said thermoset material is subject to a mechano-chemical process to regenerate an epoxide and a carboxylic acid functionality. A curative for epoxidized plant-based oils and epoxidized natural rubber is created from the reaction between a naturally occurring polyfunctional acid and an epoxidized plant-based oil is disclosed. The curative may be used to produce porosity-free castable resins and vulcanize rubber formulations based on epoxidized natural rubber. Materials made from disclosed materials may be advantageously used as leather substitutes.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of and claims priorityfrom U.S. patent application Ser. No. 16/457,352 filed on Jun. 28, 2019,which application is a continuation of and claims priority to U.S.patent application Ser. No. 16/388,693 filed on Apr. 18, 2019 (now U.S.Pat. No. 10,400,061), which application claimed priority provisionalU.S. App. Nos. 62/660,943 filed on Apr. 21, 2018; 62/669,483 filed onMay 10, 2018; 62/669,502 filed on May 10, 2018; 62/756,062 filed on Nov.5, 2018; 62/772,744 filed on Nov. 29, 2018; U.S. Pat. No. 62,772,715filed on Nov. 29, 2018; and 62/806,480 filed on Feb. 15, 2019. Thepresent application also claims priority to provisional Pat. App. Nos.62/869,393 filed on Jul. 1, 2019; and 62/989,275 filed on Mar. 13, 2020,all of which applications are incorporated by reference herein in theirentireties.

FIELD OF THE INVENTION

The present disclosure related to methods for producing natural productsthat may be made utilizing the material disclosed herein. The naturalproducts have physical properties similar to synthetic coated fabrics,leather-based products, and foam products.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

No federal funds were used to develop or create the invention disclosedand described in the patent application.

BACKGROUND

The replacement of synthetic polymeric materials with naturally derivedand biodegradable polymers is an important goal in achieving sustainableproducts and material processes. Among all potential natural startingmaterials, those that are most prevalent in nature and easily captured,separated, and purified are also the most cost-effective replacementoptions. Materials such as wood, natural fibers, natural oils, and othernatural chemicals are all readily available in bountiful amounts.Heretofore, the limitations in using natural materials more broadly aredue primarily to limitations in processing flexibility (e.g.moldability) and/or ultimate properties (e.g. strength, elongation,modulus).

Natural animal-hide leather is a versatile material for which there arefew synthetic alternatives that meet the same performance attributes.Natural animal-hide leather in particular has a unique blend offlexibility, puncture resistance, abrasion resistance, formability,breathability, and imprintability. Synthetic leather substitutematerials are known in the art. Many utilize a fabric backing and apolyurethane or plasticized polyvinyl chloride elastomeric surface—suchmaterial constructions may achieve certain performance attributes ofnatural animal-hide leather but are not all-natural and are notbiodegradable. It is desirable to have a different material thatcomprises all-natural materials or at least contains a substantialportion of all-natural content. Furthermore, it is desirable that anyleather substitute be biodegradable to avoid disposal concerns.

Memory foam materials are entirely made of synthetic polymers today. Forexample, most commercial memory foam comprises polyurethane elastomerthat utilizes foam structure. Memory foam materials are characterized bylossy behavior, i.e. the polymer has a high loss modulus (tan δ). Memoryfoam materials are generally very stiff at temperatures substantiallybelow room temperature (e.g. below 10° C.), rubbery at temperaturessubstantially above room temperature (e.g. above 50° C.), andleather/lossy at or near room temperature (e.g. 15° C.-30° C.).

Liu (U.S. Pat. No. 9,765,182) discloses an elastomeric productcomprising epoxidized vegetable oil and a polyfunctional carboxylicacid. Because such ingredients are not miscible in each other, Liudiscloses the use of an alcohol solvent that is capable of solubilizingthe polyfunctional carboxylic acid and that is miscible with theepoxidized vegetable oil. An exemplary epoxidized vegetable oildisclosed by Liu is epoxidized soybean oil. An exemplary polyfunctionalcarboxylic acid disclosed by Liu is citric acid. Exemplary alcohols usedas a solubilizing agent include ethanol, butanol, and isopropyl alcohol.Liu discloses the creation of an elastomer by dissolving citric acid inethanol and then adding the entire amount of epoxidized soybean oil tothe solution. The solution is then heated to 50° C.-80° C. for 24 hrs toremove the ethanol (assisted by vacuum). Liu discloses that the optimaltemperature range for polymerization occurred at 70° C. (without anycatalysts). The Liu disclosure is clear that the evaporation temperaturerange for the alcohol solvent and polymerization temperature areoverlapping and thus there exhibits a high risk of prematurely curingthe polymer, i.e. forming a gel, before the entirety of the solvent isremoved. We have found that elastomers prepared by the method disclosedby Liu contain substantial porosity due to the evaporation of residualalcohol solvent after the onset of polymerization.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments and together with thedescription, serve to explain the principles of the methods and systems.

FIG. 1 is a chemical reaction formula and schematic for at least oneillustrative embodiment of the curative disclosed herein.

FIG. 2A is an illustration of an epoxidized natural rubber-basedmaterial produced using a relatively lower viscosity resin that wasallowed to penetrate throughout the flannel substrate resulting in asuede or brushed-looking surface.

FIG. 2B is an illustration of an epoxidized natural rubber-basedmaterial produced using a relatively higher viscosity resin that wasallowed to only penetrate partly through the flannel substrate resultingin a glossy polished-looking surface.

FIG. 3 is an image of an epoxidized natural rubber-based materialproduced in accordance with the present disclosure.

FIGS. 4A, 4B, and 4C are views of a portion of an epoxidized naturalrubber-based material produced in accordance with the present disclosurethat may be used for construction of a wallet wherein each version ofthe epoxidized natural rubber-based material is made with a differenttexture.

FIG. 5 is a view of a plurality of pieces of am epoxidized naturalrubber-based material produced in accordance with the present disclosurethat may be used for construction of a wallet.

FIG. 6 is a view of the plurality of pieces of the epoxidized naturalrubber-based material produced in accordance with the present disclosureassembled as a simple credit card wallet or carrier having theappearance, rigidity and strength as one of ordinary skill would expectwith natural animal-hide leather.

FIG. 7 is a resin impregnated fabric that may be utilized in accordancewith the present disclosure.

FIG. 8A is a top view of a ball made according to the presentdisclosure.

FIG. 8B is a side view of a ball made according to the presentdisclosure.

FIG. 9 provides a graphical representation for two stress-strain curvesof two different ENR-based materials.

FIG. 10A provides a depiction of an ENR-based material configured withinherent functionality for engaging a belt buckle.

FIG. 10B provides a depiction of the ENR-based material from FIG. 10Aafter engagement with a belt buckle.

FIG. 11 provides a depiction of an ENR-based material having grooves andridges formed therein.

FIG. 12 provides a depiction of an illustrative embodiment of a moldingsystem that may be used for certain ENR-based materials.

FIG. 13 shows a chemical representation of a cured thermoset material.

FIG. 14 shows a chemical representation of mechano-chemicalreversibility.

FIG. 15 shows a series of images during the mechano-chemical processingof thermoset material.

FIG. 16 shows a series of rheometer data from material that isrepeatedly mechano-chemically processed.

FIG. 17 shows a series of rheometer data for increasing curetemperatures.

FIG. 18 shows pancake-like discs of foam product produced according toone embodiment of the present disclosure.

FIG. 19 shows a gradient of porosity associated with variation in curingtemperature.

DETAILED DESCRIPTION

Before the present methods and apparatuses are disclosed and described,it is to be understood that the methods and apparatuses are not limitedto specific methods, specific components, or to particularimplementations. It is also to be understood that the terminology usedherein is for the purpose of describing particular embodiments/aspectsonly and is not intended to be limiting.

As used in the specification and the appended claims, the singular forms“a,” “an,” and “the” include plural referents unless the context clearlydictates otherwise. Ranges may be expressed herein as from “about” oneparticular value, and/or to “about” another particular value. When sucha range is expressed, another embodiment includes from the oneparticular value and/or to the other particular value. Similarly, whenvalues are expressed as approximations, by use of the antecedent“about,” it will be understood that the particular value forms anotherembodiment. It will be further understood that the endpoints of each ofthe ranges are significant both in relation to the other endpoint, andindependently of the other endpoint.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where said event or circumstance occurs and instances where itdoes not.

“Aspect” when referring to a method, apparatus, and/or component thereofdoes not mean that limitation, functionality, component etc. referred toas an aspect is required, but rather that it is one part of a particularillustrative disclosure and not limiting to the scope of the method,apparatus, and/or component thereof unless so indicated in the followingclaims.

Throughout the description and claims of this specification, the word“comprise” and variations of the word, such as “comprising” and“comprises,” means “including but not limited to,” and is not intendedto exclude, for example, other components, integers or steps.“Exemplary” means “an example of” and is not intended to convey anindication of a preferred or ideal embodiment. “Such as” is not used ina restrictive sense, but for explanatory purposes.

Disclosed are components that can be used to perform the disclosedmethods and apparatuses.

These and other components are disclosed herein, and it is understoodthat when combinations, subsets, interactions, groups, etc. of thesecomponents are disclosed that while specific reference of each variousindividual and collective combinations and permutation of these may notbe explicitly disclosed, each is specifically contemplated and describedherein, for all methods and apparatuses. This applies to all aspects ofthis application including, but not limited to, steps in disclosedmethods. Thus, if there are a variety of additional steps that can beperformed it is understood that each of these additional steps can beperformed with any specific embodiment or combination of embodiments ofthe disclosed methods.

The present methods and apparatuses may be understood more readily byreference to the following detailed description of preferred aspects andthe examples included therein and to the Figures and their previous andfollowing description. Corresponding terms may be used interchangeablywhen referring to generalities of configuration and/or correspondingcomponents, aspects, features, functionality, methods and/or materialsof construction, etc. those terms.

It is to be understood that the disclosure is not limited in itsapplication to the details of construction and the arrangements ofcomponents set forth in the following description or illustrated in thedrawings. The present disclosure is capable of other embodiments and ofbeing practiced or of being carried out in various ways. Also, it is tobe understood that phraseology and terminology used herein withreference to device or element orientation (such as, for example, termslike “front”, “back”, “up”, “down”, “top”, “bottom”, and the like) areonly used to simplify description, and do not alone indicate or implythat the device or element referred to must have a particularorientation. In addition, terms such as “first”, “second”, and “third”are used herein and in the appended claims for purposes of descriptionand are not intended to indicate or imply relative importance orsignificance.

Element Description Element Number Natural leather-like material (suedefinish) 100 Natural leather-like material (glossy finish)  100′ Fabric102 Fabric extension 103 Polymer 104

1. Curative (Pre-Polymer)

Disclosed is a curative comprised of an epoxidized triglyceride (whichmay be a plant-based oil such as vegetable and/or nut oil(s) and/or amicrobial oil such as that produced by algae or yeast), naturallyoccurring polyfunctional carboxylic acids, and at least some graftedhydroxyl-containing solvent. Examples of such epoxidized triglyceridescomprised of plant-based oils include epoxidized soybean oil (ESO),epoxidized linseed oil (ELO), epoxidized corn oil, epoxidized cottonseedoil, epoxidized canola oil, epoxidized rapeseed oil, epoxidized grapeseed oil, epoxidized poppy seed oil, epoxidized tongue oil, epoxidizedsunflower oil, epoxidized safflower oil, epoxidized wheat germ oil,epoxidized walnut oil, and other epoxidized vegetable oils (EVOs).Generally, any polyunsaturated triglyceride with an iodine number of 100or greater may be epoxidized and used with the curative as disclosedherein without limitation unless otherwise indicated in the followingclaims. Such epoxidized triglycerides are generally known to bebiodegradable. Examples of naturally occurring polyfunctional acidsinclude citric acid, tartaric acid, succinic acid, malic acid, maleicacid, and fumaric acid. Although specific illustrative embodiments maydenote one type of oil and/or acid, such embodiments are not meant to belimiting in any way unless otherwise indicated in the following claims.

The curative as disclosed herein is a reaction product between anepoxidized vegetable oil(s) and a naturally occurring polyfunctionalcarboxylic acid conducted in a solvent that is capable of solubilizingboth the epoxidized vegetable oil(s) and a naturally occurringpolyfunctional carboxylic acid, wherein the solvent contains at leastsome portion of a hydroxyl-containing solvent (i.e., an alcohol) thatreacts with at least some portion of the carboxylic acid functionalgroups that are contained on the polyfunctional carboxylic acid. Thecurative is an oligomeric structure of carboxylic-acid-capped epoxidizedvegetable oil, heretofore called a pre-polymer curative. The curative isa viscous liquid that is soluble in unmodified epoxidized vegetable oiland other epoxidized plant-sourced polymers (e.g., epoxidized naturalrubber).

Generally the terms “curative,” “pre-polymer,” and “pre-polymercurative” are used to denote the same and/or similar chemical structureas disclosed in this Section 1. However, the function of the curative,pre-polymer, and pre-polymer curative may be different in differentapplications thereof to produce different end products. For example,when the curative is used with epoxy-containing monomeric resins (e.g.,EVOs) it functions to build molecular weight that is integral to thebackbone of the resultant polymer and therefore may be referred to as apre-polymer in such applications. In another example, when the curativeis used in applications having pre-existing high molecular weightepoxy-containing polymer (e.g., as disclosed below herein) the curativeis functioning primarily to link those pre-existing high molecularweight polymers and therefore may be referred to simply as a curative insuch applications. Finally, when the curative is used in applicationshaving both substantial amounts of epoxy-containing monomer and someportion of pre-existing high molecular weight epoxy-containing polymerit functions both to build molecular weight and to link pre-existinghigh molecular weight polymers and therefore may be referred to as apre-polymer curative.

It has been found that the creation of a curative can eliminate the riskof porosity due to solvent evaporation during the curing process.Furthermore, the oligomeric curative may incorporate substantially allof the polyfunctional carboxylic acid so that no additional curative isrequired during the curing process. For example, citric acid is notmiscible in epoxidized soybean oil (ESO) but they may be made to reactwith each other in a suitable solvent. The amount of citric acid may beselected so that the curative is created so that substantially all ofthe epoxide groups of the ESO in the curative are reacted withcarboxylic acid groups of the citric acid. With sufficiently excesscitric acid, the pre-polymerization extent may be limited so that no gelfraction is formed. That is, the target species of the curative is a lowmolecular weight (oligomeric) citric-acid capped ester-product formed bythe reaction between carboxylic acid groups on the citric acid withepoxide groups on the ESO. The solvent used for the reaction mediumcontains at least some portion of a hydroxyl-containing solvent (i.e.,an alcohol) that is grafted unto at least some of the polyfunctionalcarboxylic acid during the creation of the curative. Although specificillustrative embodiments may denote one type of alcohol (e.g., IPA,ethanol, etc.), such embodiments are not meant to be limiting in any wayunless otherwise indicated in the following claims.

Illustrative oligomeric curatives may be created with weight ratios ofESO to citric acid in the range of 1.5:1-0.5:1, which corresponds to amolar ratio of epoxide groups:carboxylic acid groups of approximately0.43:1 (for a weight ratio of 1.5:1) to 0.14:1 (for the weight ratio of0.5:1). In one illustrative embodiment a weight ratio of ESO:citric acidis 1:1, which gives a molar ratio of epoxide groups:carboxylic acidgroups of 0.29:1. If too much ESO is added during curative creation, thesolution may gel and further incorporation of ESO to create the targetresin becomes impossible. Note that on a weight basis, stoichiometricequivalent amounts of epoxide groups on the ESO (molecular weight ofapproximately 1000 g/mol, functionality of 4.5 epoxide groups permolecule) and carboxylic acid groups on the citric acid (molecularweight 192 g/mol, functionality of 3 carboxylic groups per molecule)occur at a weight ratio of 100 parts of ESO to about 30 parts of citricacid. A weight ratio of ESO:citric acid above 1.5:1 may build a curativewith excessive molecular weight (and hence viscosity) which limits itsability to be incorporated into unmodified epoxidized vegetable oil orepoxidized natural rubber. If the weight ratio of ESO:citric acid isbelow 0.5:1 it has been found that there is so much excess citric acidthat after solvent evaporation, ungrafted citric acid may precipitateout of solution.

In addition to controlling the ratio of ESO to citric acid, throughexperimentation it has been found that selective control of the amountof alcohol used as a solvent may also be used to tailor the physicalproperties of the resulting elastomer made with the curative. Thealcohol solvent itself is incorporated into the elastomer by formingester linkages with the polyfunctional carboxylic acid. A mixture of twoor more solvents may be used to tailor the amount of grafting of ahydroxyl-containing solvent onto the citric acid-capped oligomericcurative. A schematic depiction of the chemical reaction for making anillustrative embodiment of the curative disclosed herein is shown inFIG. 1.

For example, and without restriction or limitation, isopropyl alcohol(IPA), ethanol, or other suitable alcohol without limitation unlessotherwise indicated in the following claims may be used as a componentof a solvent system used to miscibilize citric acid with ESO. IPA,ethanol, or other suitable alcohol are capable of forming an esterlinkage via a condensation reaction with citric acid. Since citric acidhas three carboxylic acids, such grafting reduces the averagefunctionality of the citric acid molecules that are reacting with theESO. This is beneficial in creating an oligomeric structure that is morelinear and therefore less highly branched. Acetone may be used as onecomponent of a solvent system used to miscibilize citric acid with ESO,but unlike IPA or ethanol, acetone itself is not capable of beinggrafted onto the citric acid-capped oligomeric curative. Indeed, duringcreation of the oligomeric curative it has been found that thereactivity of the pre-polymer is determined, in part, by the ratio ofthe alcohol to acetone that may be used to solubilize citric acid withESO. That is, in reaction mixtures with the similar amounts of citricacid and ESO, a curative created from a solution with a relatively highratio of alcohol to acetone creates a curative with longer,less-highly-branched structures than curative created from a solutionwith a relatively low ratio of alcohol to acetone under similar reactionconditions.

Generally, a curative may be adapted for use with additional unmodifiedepoxidized vegetable oil to yield a castable resin. The improvedmethodology disclosed by Applicant herein results in substantiallyporosity-free elastomeric products.

2. Coated Materials

A. Summary

The curative as disclosed immediately above may function as apre-polymer and may be mixed with additional epoxidized vegetable oil tobe used as a resin which may be applied to various backingmaterials/backing layers to yield a leather-like material with excellenttear strength, flexibility, dimensional stability, and fabricationintegrity. Throughout this disclosure, the terms “backing material” and“backing layer” may be used interchangeably depending the specificcontext. However, for certain articles disclosed herein a backingmaterial may be comprised of a resin-impregnated backing layer.According to one illustrative embodiment of a coated material utilizingthe pre-polymer, one illustrative fabric backing material/backing layermay be a woven cotton flannel (as depicted in FIGS. 2A & 2B anddescribed in more detail below). If the resin is formulated to berelatively low in viscosity, exposed flannel may persist above theresin-coated fabric core. This imparts a warm texture to the surface ofthe article. Other fabric backing material/backing layer may includewoven substrates of various kinds (e.g., plain weave, twill, sateenweave, denim), knitted substrates, and non-woven substrates withoutlimitation unless indicted in the following claims.

In other embodiments, the resin may be coated onto a non-stick surface(e.g., silicone or PTFE) or texture paper at a consistent layerthickness. After the film has been coated to an even layer, a layer ofbacking material may be laid on top of the liquid resin. The liquidresin may wick into the fabric layer (i.e., backing material) creating apermanent bond with the fabric during curing. The article may then beplaced in an oven to complete the cure of the resin. Temperatures forcuring may be preferably 60° C.-100° C., or even more preferably 70°C.-90° C. for a duration of 4 hr-24 hr. Longer cure times are alsopermissible. Alternatively, the liquid resin may be applied onto anon-stick surface (e.g., silicone or PTFE) or texture paper at aconsistent layer thickness after which fabric may be laid on top of theliquid resin and then another non-stick surface may be laid on top ofthe resin and fabric. This assembly may be placed in a heated moldingpress to complete the cure. Cure temperatures within a press mayoptionally be higher than in an oven because the molding pressureminimizes the creation of bubbles (voids) in the final article. Curetemperatures within a press may be between 80° C.-170° C., or even morepreferably, 100° C.-150° C. for a duration of 5 minutes-60 minutes, ormore preferably between 15 minutes-45 minutes.

The resin may be optically clear with a slight yellow hue. Resin thathas no pigment added may be used to create oil-cloth like materials thatallow for fabrics to be made water resistant and wind resistant whilestill allowing the fabric patterns to be visible within the resin.Coated fabrics made according to this embodiment may be cured either inan oven (without press molding) or may be cured within a heated press.Such coated fabrics may be used for garments, particularly forouterwear, or for waterproof accessories; including, but not limited to,purses, handbags, backpacks, duffle bags, luggage, briefcases, hats, andthe like.

Novel embossed items have been created using the resin described in thisdisclosure in combination with non-woven mats comprised of virgin orrecycled textile fibers. Specifically, non-woven webs from about 7 mmthick to about 20 mm thick may be impregnated by resins preparedaccording to this disclosure. After impregnation, the non-woven webs maybe pressed in a heated hydraulic press to a nominal pressure of between10 psi-250 psi, or even more preferably between 25 psi-100 psi. Thenon-woven web with resin may be pressed between silicone release liners,one of which may have an embossing pattern therein. The embossingpattern may have relief characteristics of a depth between 1 mm-6 mm, ormore preferably between 2 mm and 4 mm in depth. When resin preparedaccording to this disclosure is further pigmented with a structuralcolor pigment, e.g., mica pigments of various shades—many of which havepearlescent qualities—and such resin is molded into a non-woven web withan embossing pattern, it has been found to create aesthetically pleasingpatterned articles. The structural color has been found topreferentially align at embossing features to create sharp contrasts andvisual depth corresponding to the embossed pattern. Alternatively, andwithout restriction unless so indicated in the following claims, mineralpigments from other source rocks and processes may be included in thecasting resin to impart color to articles made according to the presentdisclosure.

Resin coated fabrics made also be created according to one embodiment ofthe present disclosure using roll-to-roll processing. In a roll-to-rollprocess of textured, coated fabrics, including leather-like materials,the texture paper is often used as a carrier film to move both the resinand the fabric through an oven for a specific duration of time. Theresin according to the present disclosure may require cure times thatare longer than PVC or polyurethane resins that are currently used inthe art, thus the line speeds may be correspondingly slower or the cureovens may be made longer to effect a longer cure time. Vacuum degassingof the resin prior to casting may allow for higher temperatures to beused for curing (due to less residual solvent, moisture, and trappedair) that would speed up the cure time and thus the line pull rate.

Alternatively, certain catalysts are known in the art to speed up thecarboxylic acid addition to epoxide groups. Base catalysts may be addedto the resin; some example catalysts include pyridine, isoquinoline,quinoline, N,N-dimethylcyclohexylamine, tributylamine,N-ethylmorpholine, dimethylaniline, tetrabutyl ammonium hydroxide, andsimilar molecules. Other quaternary ammonium and phosphonium moleculesare known catalysts for the carboxylic acid addition to epoxide groups.Various imidazoles are likewise known as catalysts for this reaction.Zinc salts of organic acids are known to improve the cure rate as wellas impart beneficial properties, including improved moisture resistance,to the cured films. (See Werner J. Blank, Z. A. He and Marie Picci,“Catalysis of the Epoxy-Carboxyl Reaction”, Presented at theInternational Waterborne, High-Solids and Powder Coatings Symposium,Feb. 21-23, 2001.) Accordingly, any suitable catalyst may be usedwithout limitation unless otherwise indicated in the following claims.

B. Illustrative Embodiments

Although the illustrative embodiments and methods that follow includespecific reaction parameters (e.g., temperatures, pressures, reagentratios, etc.), those embodiments and methods are for illustrativepurposes only and in no way limit the scope of the present disclosureunless otherwise indicated in the following claims.

First Illustrative Embodiment and Method

To make a first illustrative embodiment of a coated material using thepre-polymer (that is, the curative as disclosed previously above), 18parts of citric acid were dissolved into 54 parts of warm IPA. To thissolution, only 12 parts of ESO is added. The IPA was evaporated withcontinuous heating and stirring (above approximately 85° C.). This wasfound to make a viscous liquid that could be heated to above 120° C.without gelation (even for long periods of time). This viscous liquidpre-polymer was allowed to cool below 80° C. To this viscous liquid, 88parts of ESO is added. The final liquid resin will polymerize to a solidelastomeric product in 1-5 minutes at approximately 150° C. The coatedmaterial (which may serve as a substitute for natural animal-hideleather) may be formed as a reaction product using an epoxidizedtriglyceride and the pre-polymer without limitation unless otherwiseindicated in the following claims.

Second Illustrative Embodiment and Method

For this illustrative embodiment, 30 parts of citric acid were dissolvedinto 60 parts of warm IPA. To this solution, 20 parts of ESO were slowlyadded while stirring. The IPA was evaporated with continuous heating andstirring (above 85° C., and preferably above 100° C.). This viscouspre-polymer was allowed to cool below 80° C. (preferably below 70° C.)and 80 parts of ESO were added along with various structural colorpigments and 0.5 parts of zinc stearate (as an internal mold releaseagent). The resulting resin was poured over cellulosic fabric andallowed to cure at approximately 120° C. for 10-30 minutes. Afterinitial cure, the material was placed in an 80° C. oven for overnightpost-curing (approximately 16 hours). The surface of the material wasthen sanded smooth (and optionally polished). The resulting material wasfound to have leather-like attributes.

Third Illustrative Embodiment and Method

Pre-polymer creation has been conducted by dissolving 50 parts of citricacid in 100 parts of warm IPA, accelerated by mixing. After dissolutionof the citric acid, 50 parts of ESO is added to the stirring solution.The mixture is kept on a hot plate while the IPA evaporated undercontinuous heat and stirring. Such solutions have been created multipletimes with various hot plate temperatures and air flow conditions. Evenafter extended times of heating and stirring, it has repeatedly beenfound that the amount of reaction product is greater than the mass ofthe ESO and citric acid alone. Depending on the rate of IPA evaporation(determined at least by air flow, mixing rate, and hot platetemperature) between 2.5 and 20 parts of the IPA has been found to begrafted onto the citric-acid capped oligomeric pre-polymer. Furthermore,solvent blends of acetone and IPA may be used as the reaction mediumwherein the ratio between acetone and IPA determines the amount ofresidual carboxylic acid functional groups on the pre-polymer as well asthe amount of branching in the pre-polymer. Higher amounts of IPA createmore linear structures by lowering the effective functionality of thecitric acid by capping some of the carboxylic acid functional groups bygrafting IPA unto the citric acid via an ester linkage as referenced inFIG. 1. Lower amounts of IPA create more highly branched structures withmore residual carboxylic acid functional groups.

Fourth Illustrative Embodiment and Method

Pre-polymer creation has been conducted by dissolving 50 parts of citricacid in 100 parts of warm IPA, accelerated by mixing. After dissolutionof the citric acid, 50 parts of ESO and 15 parts of dewaxed blondeshellac is added to the stirring solution. The mixture is kept on a hotplate the while IPA evaporated under continuous heat and stirring. Theshellac was found to increase the viscosity of the resultingpre-polymer.

Fifth Illustrative Embodiment and Method

Pre-polymer creation has been conducted by dissolving 45 parts of citricacid in 90 parts of warm IPA, accelerated by mixing. After dissolutionof the citric acid, 45 parts of ESO is added to the stirring solution.The mixture is kept on a hot plate while the IPA evaporated undercontinuous heat and stirring.

Sixth Illustrative Embodiment and Method

Pre-polymer creation has been conducted by dissolving 45 parts of citricacid in 30 parts of warm IPA and 60 parts of acetone, accelerated bymixing. After dissolution of the citric acid, 45 parts of ESO is addedto the stirring solution. The mixture is kept on a hot plate while theacetone and IPA evaporated under continuous heat and stirring. Suchsolutions have been created multiple times with various hot platetemperatures and air flow conditions. Even after extended times ofheating and stirring, it has repeatedly been found that the amount ofreaction product is greater than the mass of the ESO and citric acidalone, but the amount of grafted IPA is less than in pre-polymer createdaccording to the fifth illustrative embodiment (even though the ratio ofESO:citric acid is 1:1 in both cases). Furthermore, pre-polymer createdaccording to the fifth illustrative embodiment is lower in viscositycompared to pre-polymer created according to the sixth illustrativeembodiment.

Generally, it is contemplated that the greater content of IPA during thepre-polymer creation allowed more IPA to be grafted onto carboxylic-acidsites on the citric acid, thus lowering the average functionality of thecitric acid and thus creating a less highly branched oligomericpre-polymer. In no circumstance have reaction conditions been found thatcapping of the citric acid with IPA to such an extent that final curingof the resin is prohibited.

Seventh Illustrative Embodiment and Method

The pre-polymer created in the fourth illustrative embodiment was mixedwith additional ESO to bring the total calculated amount of ESO to 100parts. This mixture was found to cure into a transparent, elastomericresin. Tensile testing according to ASTM D412 found that the tensilestrength was 1.0 MPa with an elongation at break of 116%.

Eight Illustrative Embodiment and Method

Pre-polymer was created by dissolving 45 parts of citric acid in 20parts of IPA and 80 parts of acetone under heating and stirring. Afterdissolution of the citric acid, 35 parts of ESO was added to thesolution along with 10 parts of shellac. The pre-polymer created afterevaporation of the solvents was then cooled. The pre-polymer was mixedwith an additional 65 parts of ESO to bring the total amount of ESO to100 parts. The mixed resin was then cast on a silicone mat to make atransparent sheet. The mechanical properties of the material were foundby tensile testing according to ASTM D412. The tensile strength wasfound to be 1.0 MPa and the elongation was 104%, which gives acalculated modulus of 0.96 MPa.

Ninth Illustrative Embodiment and Method

Pre-polymer was created by dissolving 45 parts of citric acid in 5 partsof IPA and 80 parts of acetone under heating and stirring. Afterdissolution of the citric acid, 35 parts of ESO was added to thesolution along with 10 parts of shellac. The pre-polymer created afterevaporation of the solvents was then cooled. The pre-polymer was mixedwith an additional 65 parts of ESO to bring the total amount of ESO to100 parts. The mixed resin was then cast on a silicone mat to make atransparent sheet. The mechanical properties of the material were foundby tensile testing according to ASTM D412. The tensile strength wasfound to be 1.8 MPa and the elongation was 62%, which gives a calculatedmodulus of 2.9 MPa. As can be seen from the eighth and ninthillustrative embodiments, the lower amount of IPA present duringpre-polymer creation yields a pre-polymer that creates a more highlycrosslinked resin with higher modulus and lower elongation. Thesereaction products are more plastic-like and less rubber-like in theirmaterial attributes.

Tenth Illustrative Embodiment and Method

Pre-polymer was created by dissolving 25 parts of citric acid in 10parts of IPA and 80 parts of acetone under heating and stirring. Afterdissolution of the citric acid, 20 parts of ESO was added to thesolution along with 5 parts of shellac. The pre-polymer created afterevaporation of the solvents was then cooled. The pre-polymer was mixedwith an additional 80 parts of ESO to bring the total amount of ESO to100 parts. The mixed resin was then cast on a silicone mat to make atransparent sheet. The mechanical properties of the material were foundby tensile testing according to ASTM D412. The tensile strength wasfound to be 11.3 MPa and the elongation was 33%, which gives acalculated modulus of 34 MPa. As can be seen from the tenth illustrativeembodiment, by appropriate design of the pre-polymer and the final resinmixture, a plastic material with the attributes of high strength andhigh modulus may be created by the methods of the present disclosure.

Eleventh Illustrative Embodiment and Method

The pre-polymer of the sixth illustrative embodiment was mixed withadditional ESO to bring the total calculated amount of ESO to 100 parts.The mixed resin was then cast on a silicone mat to make a transparentsheet. The mechanical properties of the material were found by tensiletesting according to ASTM D412. The tensile strength was found to be 0.4MPa and the elongation was 145%, which gives a calculated modulus of0.28 MPa.

As can be seen from the eleventh illustrative embodiment, by appropriatedesign of the pre-polymer and the final resin mixture, a high elongationelastomeric material by be created by the methods of the presentdisclosure. Therefore, by appropriate design of the pre-polymer, theinventive methods may be used to produce materials ranging from stiff,plastic-like materials to high-elongation elastomeric materials.Generally, higher amounts of IPA grafted during pre-polymer formationlowers the stiffness of the resulting material. Higher amounts ofdissolved shellac yield stronger materials with somewhat higherstiffness. Citric acid amount (relative to the final mixed recipe) maybe used either above stoichiometric balance or below to lower themodulus. Citric acid amounts near stoichiometric balance (approximately30 parts by weight to 100 parts by weight ESO) generally yield thestiffest materials; unless offset by high levels IPA grafting of thecarboxylic acid groups during pre-polymer formation.

One of the beneficial attributes of animal-based leather is itsflexibility over a wide range of temperatures. Synthetic-polymer basedleather substitutes based on PVC or polyurethane may become particularlystiff at temperatures below −10° C. or below −20° C. (based on testingaccording to CFFA-6a—Cold Crack Resistance—Roller method). Materialsprepared according to some of the embodiments of the present disclosuremay have poor cold crack resistance. In the following examples,formulations are given that improve cold crack resistance. Cold crackresistance may be improved by adding a flexible plasticizer. Somenatural vegetable oils may exhibit good low temperature flow, especiallypreferred may be polyunsaturated oils. Such oils may be anynon-epoxidized triglycerides (such as those disclosed in Section 1above) having relatively high iodine numbers (e.g., greater than 100)without limitation unless otherwise indicated in the following claims.Alternatively, monounsaturated oils may be added as plasticizers; oneillustrative oil may be castor oil which is found to be thermally stableand less prone to becoming rancid. Additionally, the fatty acids andfatty acid salts of these oils may be used as a plasticizer.Accordingly, the scope of the present disclosure is in no way limited bythe presence of or particular chemistry of a plasticizer unlessotherwise indicated in the following claims.

Another approach is to use a polymeric additive that may impart improvedlow temperature flexibility. A preferred polymeric additive may beEpoxidized Natural Rubber (ENR). ENR is available commercially indifferent grades with various levels of epoxidation, for example 25%epoxidation of the double bonds yields grade ENR-25, 50% epoxidation ofthe double bonds yields grade ENR-50. Higher levels of epoxidationincrease the glass transition temperature, T_(g). It is advantageous forthe T_(g) to remain as low as possible for the most improvement in coldcrack resistance in the final resin, so ENR-25 may be the preferredgrade for use as a polymeric plasticizer. Even lower levels ofepoxidation may be advantageous for further lowering of the cold cracktemperature in the final resin. However, the scope of the presentdisclosure is not so limited unless otherwise indicated in the followingclaims.

Twelfth Illustrative Embodiment and Method

ENR-25 was mixed with ESO on a two-roll rubber compounding mill. It wasfound that ESO could slowly be added until a total of 50 parts of ESOcould be added to 100 parts of ENR-25 before the viscosity dropped sofar that further mill mixing was impossible. This gooey material wasthen transferred to containers for further mixing in a Flacktek®Speedmixer. A flowable mixture was achieved when a total of 300 parts ofESO was finally incorporated into 100 parts of ENR-25. The mixturecreated did not phase segregate.

The material of the twelfth illustrative embodiment may be mixed in asingle step by a number of means known in the art, without restrictionor limitation unless indicated in the following claims. Specifically,so-called Sigma Blade mixers may be used to create a homogenous mixtureof ENR and ESO in a single step. Likewise, a kneader, such as a BussKneader, by used to create such mixtures in a continuous mixer-typearrangement which is well known to one of ordinary skill in the art. Thehomogeneous mixture may be mixed with pre-polymers as described in priorexamples to create a spreadable resin that may be used as a leather-likematerial with improved cold crack resistance. Additionally, materialscreated with ENR-modified ESO as disclosed by the twelfth illustrativeembodiment may exhibit improved tear strength, elongation, and abrasionresistance when compared to resins that do not contain ENR.

C. Additional Treatments

Articles produced according to this disclosure may be finished by anymeans known in the art. Such means include, but are not limited to,embossing, branding, sanding, abrading, polishing, calendering,varnishing, waxing, dyeing, pigmenting, and the like unless otherwiseindicated in the following claims. Exemplary results may be obtained byimpregnating the resin of the present disclosure onto fabric or anon-woven mat and curing such article. After curing the article, thesurfaces may be sanded to remove imperfections and expose some portionof the substrate. Such surfaces exhibit characteristics very analogousto animal-hide leather, as exemplified by FIGS. 3-7. The surfaces thenmay be treated with natural oil or wax protectants, subject to aparticular application.

D. Applications/Illustrative Products

Coated fabrics, ENR-based materials, and/or oil cloth-like materialsproduced according to the present disclosure may be used in applicationswhere animal-hide leather and/or synthetic resin-coated fabrics are usedtoday. Such applications may include belts, purses, backpacks, shoes,table tops, seating, and the like without limitation unless otherwiseindicated in the following claims. Many of these articles are consumableitems that if made from synthetic material alternatives arenon-biodegradable and are non-recyclable. If such items are instead madeaccording to the present disclosure, they would be biodegradable andthus not create a disposal problem as the biodegradability of similarlyprepared polymers made from ESO and natural acids has been studied andshown. Shogren et al., Journal of Polymers and the Environment, Vol. 12,No. 3, July 2004. Furthermore, unlike animal-hide leather, whichrequires significant processing to be made durable and stable (some ofwhich uses toxic chemicals), the materials disclosed herein may requireless processing and will use environmentally friendly chemicals.Additionally, animal-hide leather is limited in size and may containdefects that render large pieces inefficient to produce. The materialdisclosed herein does not have the same kind of size limitations.

A cross-sectional depiction of the resulting material when a liquidresin precursor such as those described for various illustrativeembodiments and methods above was applied to cotton flannel fabric thatwas placed over a heated surface (a hot plate) is shown in FIGS. 2A &2B. The resin was found to react in 1-5 minutes when the surfacetemperature of the hot plate was approximately 130° C.-150° C. Theviscosity of the resin may be controlled by the time allowed forpolymerization prior to pouring over the surface. By controlling theviscosity, the degree of penetration into the surface may be controlledto achieve various effects in the resultant product. For example, alower viscosity resin may penetrate throughout the fabric 102 and leavea suede or brushed-looking surface as shown in FIG. 2A to create anatural leather-like material 100 having a suede finish. A higherviscosity resin may penetrate only partly through the fabric 102 andresult in a glossy, polished-looking surface as shown in FIG. 2B tocreate a natural leather-like material 100′ having a glossy finish. Inthis way, variations may be created that mimic natural animal-hideleather products. As shown in contrasting FIGS. 2A & 2B, the naturalleather-like material 100 having a suede finish 100 may exhibit a largernumber of fabric extensions 103 extending from the fabric 102 throughthe polymer 104 than does the natural leather-like material 100′ havinga glossy finish. In the natural leather-like material 100′ having aglossy finish, the majority of fabric extensions 103 may terminatewithin the polymer 104.

Alternatively, an article with a suede-like (i.e., relatively soft)surface without resin may be created by embedding flannel in anon-miscible paste (e.g., silicone vacuum grease) that is coated on ahot plate. The resin can then be poured over the surface of the flannelbut will not penetrate through the non-miscible paste. After curing, thenon-miscible paste may be removed from the article leaving that surfacewith a suede-like feeling. One of ordinary skill will thereforeappreciate that a natural leather-like material as disclosed herein maybe produced as the reaction product between an epoxidized vegetable oiland a naturally occurring polyfunctional acid impregnated upon a cottonflannel substrate, without limitation or restriction, wherein thearticle thus formed has the reaction product impregnated only partlythrough the substrate with substantially unimpregnated flannel on oneside of the article. Although cotton flannel was used in these examples,any suitable flannel and/or fabric may be used including but not limitedto those made from linen, hemp, ramie, and other cellulosic fiberswithout limitation unless otherwise indicated in the following claims.Additionally, non-woven substrates may be used as well recycledsubstrates (upcycled). Brushed knits may be used to impart additionalstretch to the resultant article. Random mats (e.g., Pellon, also knownas batting) may be advantageously used as a substrate for certainarticles. In another illustrative embodiment, a textile backing layerand/or backing material may be configured from a protein-based fiber,which fibers include but are not limited to of wool, silk, alpaca fiber,qiviut, vicuna fiber, llama wool, cashmere, and angora unless otherwiseindicated in the following claims.

Additional illustrative products that may be made according to thepresent disclosure are shown in FIGS. 3-8B. A depiction of a sheet ofmaterial that may serve as a natural leather-like material is shown inFIG. 3, and FIGS. 4-6 show various natural leather-like materials thatmay be used to construct a wallet. The material in FIGS. 4A, 4B, & 4C isshown with a plurality of apertures made therein, which apertures may bemade with a conventional drill without limitation unless otherwiseindicated in the following claims. Contrasting FIGS. 4A, 4B, & 4C showsthat the method for making the material may be configured to impart awide variety of textures thereon, which textures include but are notlimited to smooth, grainy, soft, etc. (e.g., similar to that of variousanimal-hide leathers) unless otherwise indicated in the followingclaims.

The material pieces shown in FIGS. 5 & 6 may be cut using a lasercutter. Unlike animal-hide leather, the laser cutting did not char ordegrade the edges of the natural leather-like material along thecutline. A finished wallet constructed of a natural leather-likematerial made according to the present disclosure is shown in FIG. 6.The separate pieces shown in FIG. 5 may be conventionally assembled(e.g., sewn) to construct a simple credit card wallet or carrier (asshown in FIG. 6) having the appearance, rigidity, and strength as onewould expect in a similar article made from animal-hide leather. Thenatural leather-like material may be sewn and/or otherwise processedinto a finished product using conventional techniques without limitationunless otherwise indicated in the following claims. As shown in FIG. 7and as described in detail above, a fabric may be impregnated with aresin to provide various characteristics to an article made according tothe present disclosure.

Additionally, the resin produced according to the present disclosure maybe pigmented to match the coloration of natural animal-hide leather. Ofparticular utility are structural color pigments and/or mineral pigmentsthat do not contain any harmful substances. One such example ofillustrative structural color pigments is Jaquard PearlEx® pigments. Ithas been found that the blending of structural color pigments atrelatively low loadings creates a natural leather-like material that hasexcellent visual aesthetics. Another such illustrative example of asuitable pigment may be procured from Kreidezeit Naturfarben, GmbH.Furthermore, it has been found that lightly sanding the resultantsurface results in a material that strongly resembles tanned & dyedanimal-hide leather.

Although the examples disclosed utilized only one layer of fabric, otherillustrative samples have been created with multiple fabric layers tocreate thicker leather-like products. Since the reaction between epoxidegroups and carboxylic groups does not create any condensationby-products, there is no inherent limit to the cross-sectional thicknessthat may be created.

Resin-coated fabrics and non-wovens are used in applications such asoffice furniture, including seating, writing surfaces, and roomdividers; in garments, including jackets, shoes, and belts; in accessoryitems, including handbags, purses, luggage, hats, and wallets; and maybe useful in residential decorations, including wallcoverings, floorcoverings, furniture surfaces, and window treatments. Currentapplications that are served by animal-based leather may be consideredpotential applications for materials made according to the presentdisclosure.

Furthermore, current applications that are served by petrochemical-basedflexible films; notably those served by PVC and polyurethane-coatedfabrics, may be considered potential applications for materials madeaccording to the present disclosure. In addition, the resin as disclosedherein is substantially free of any off-gassing vapors when curedaccording to the times and temperatures as disclosed herein. Therefore,applications that are thicker than traditional films may also be servedby the resins prepared according to the present disclosure. For example,the resin may be used to cast three-dimensional items in suitable molds.A top view of such a three-dimensional item configured as a ball madeaccording to the present disclosure is provided in FIG. 8A, and a sideview thereof is shown in FIG. 8B. The ball may be resin-based and may beproduced from epoxidized soy oil and citric acid-based recipes alongwith structural color pigments. Simple tests indicate it has very lowrebound and is expected to have excellent vibration absorptionqualities.

Prior art three-dimensional cast resin items are typically made ofstyrene-extended polyester (orthophthallic or isophthalic systems). Suchitems may currently consist of two-part epoxies or two-part polyurethaneresins. Such items may currently consist of silicone casting resins. Oneexample of an application currently served by two-part epoxies is thethick-film coating of tables and decorative inlays, wherein the epoxymay be selectively pigmented to create a pleasing aesthetic design. Suchapplications have been successfully duplicated with casting resinscreated according to the present disclosure. Furthermore, small chesspieces have been successfully cast from resins created according to thepresent disclosure without detrimental off-gassing or trapped air.Accordingly, a wide array of applications exist for various materialsmade according to the present disclosure and the specific intended useof the final article produced by any method disclosed herein is notlimited to a particular application unless otherwise indicated in thefollowing claims.

3. Epoxidized Rubber

A. Summary

Coated fabrics prepared as disclosed in Section 2 above use a liquidousviscosity resin that allows such materials to flow into fabric andnon-woven substrates. The resulting cured materials have mechanicalproperties that reflect highly-branched structures with limited polymerflexibility between crosslinks (modest strength and modest elongation).One means of increasing the mechanical properties is to begin withpolymeric materials that have more linear structures and can be curedwith lower cross-link density. The incorporation of shellac resin (whichis a high molecular weight natural resin) in coated fabric recipes wasfound to improve strength and elongation but was also found to make thematerials more plastic. Material formulations as disclosed in Section3—Epoxidized Rubber are able to exhibit excellent mechanical properties(very high strength and higher elongation) without compromising materialflexibility at room temperature.

A natural material based on epoxidized natural rubber (ENR) is disclosedthat contains no animal-based substances and is substantially free ofpetrochemical-containing materials. In certain embodiments this naturalmaterial may serve as a leather-like material (which may be a substitutefor animal-hide leather and/or petrochemical-based leather-like products(e.g., PVC, polyurethane, etc.) without limitation unless otherwiseindicated in the following claims. Furthermore, the natural materialbased on ENR as disclosed herein may be configured to be substantiallyfree of allergens that may cause sensitivity in certain people. Thematerial disclosed herein is more cost effective and scalable than otherproposed materials for petrochemical-free vegan leather. With certaintreatments the natural material may also be made water resistant, heatresistant, and retain flexibility at low temperatures. This set ofbeneficial attributes may apply to any natural material based on ENRthat is produced according to the present disclosure and to whichadditional treatments are applied, as suitable to a particularapplication, as disclosed and discussed herein.

In at least one embodiment, an elastomeric material may be formed toinclude at least a primary polymeric material further comprised ofepoxidized natural rubber and a curative comprised of a reaction productbetween a polyfunctional carboxylic acid and an epoxidized vegetable oilas disclosed in Section 1—Curative. The elastomeric material may also beformed wherein the primary polymeric material is greater in volumetricproportion in comparison to the curative. The elastomeric material mayalso be formed to wherein the epoxidized natural rubber has a degree ofepoxidation between 3% and 50% without limitation unless otherwiseindicated in the following claims. Another embodiment of the elastomericmaterial may be comprised of a primary polymeric material comprised ofepoxidized natural rubber and a cure system that is not sulfur-based norperoxide-based, and wherein the cure system contains over 90% reactantsfrom biological sources.

In another embodiment, an article may be formed from the reactionproduct of epoxidized natural rubber and a curative wherein the curativeis the reaction product between a naturally occurring polyfunctionalcarboxylic acid and an epoxidized vegetable oil. In another embodiment,an article comprised of epoxidized natural rubber with fillers includingcork powder and precipitated silica may be formed and the article may bemolded as a sheet with leather-like texture. In another embodiment, anarticle may be formed wherein the reaction product further containsfillers of cork powder and silica. In another embodiment, the articlemay be formed or configured such that two or more layers of the reactionproduct have substantially different mechanical properties and themechanical property differences are due to differences in fillercomposition.

B. Illustrative Methods and Products

Epoxidized natural rubber (ENR) is a commercially available productunder the tradename Epoxyprene® (Sanyo Corp.). It is available in twogrades with 25% epoxidation and 50% epoxidation, ENR-25 and ENR-50respectively. However, in certain embodiments it is contemplated that anENR with a level of epoxidation between 3% and 50% may be used withoutlimitation unless otherwise indicated in the following claims. One ofordinary skill will appreciate that ENR may also be produced fromprotein denatured or removed latex starting products. During theepoxidation of natural rubber, it has been found that the allergenactivity is significantly reduced—the literature for Epoxyprenediscloses that the Latex Allergen Activity is only 2-4% of that ofuntreated natural rubber latex products. This is a substantialimprovement for those that may experience latex allergies. ENR is usedin materials of the present disclosure to impart elongation, strength,and low temperature flexibility to the products disclosed and claimed.

ENR is traditionally cured with chemistries that are common in therubber compound literature, e.g., sulfur cure systems, peroxide curesystems, and amine cure systems. According to the present disclosure, aspecially prepared curative with carboxylic acid functionality isprepared to be used as the curative as fully disclosed in Section 1above. There are a number of naturally-occurring polyfunctionalcarboxylic acid containing molecules, including but not limited tocitric acid, tartartic acid, succinic acid, malic acid, maleic acid, andfumaric acid. None of these molecules are miscible in ENR and thus havelimited effectivity and utility. It has also been found that a curativeof, for example, citric acid, and an epoxidized vegetable oil may beprepared that is soluble in ENR. Specifically, curatives of epoxidizedsoybean oil (ESO) and citric acid have been prepared with an excess ofcitric acid to prevent gelation of the ESO. Citric acid itself is notmiscible in ESO, but it has been advantageously been discovered thatsolvents such as isopropyl alcohol, ethanol, and acetone (for examplebut without limitation unless otherwise indicated in the followingclaims) may make a homogeneous solution of citric acid and ESO. In thissolution, the excess citric acid is made to react with the ESO andcreate a carboxylic-acid-capped oligomeric material (that is stillliquid) as shown in FIG. 1. The miscibilizing solvent contains at leastsome hydroxyl-containing (i.e., alcohol) solvent that at least partiallyreacts with some of the carboxylic acid functional groups on the citricacid. The majority of the solvent is removed with elevated temperatureand/or vacuum—leaving behind a curative that may be used as a misciblecurative for the ENR. By thus constructing the curative, the resultantmaterial is substantially free of petrochemical-sourced inputs.

First Illustrative Embodiment and Process for the Creation of Curativethat is Used in the Preparation of ENR-Based Material

Curative was prepared by dissolving 50 parts of citric acid in a warmblend of 50 parts of isopropyl alcohol and 30 parts of acetone. Afterthe citric acid was dissolved, 15 parts of shellac flakes (blondedewaxed) were added to the mixture along with 50 parts of ESO. Themixture was heated and stirred continually until all the volatilesolvents had evaporated. It is noteworthy that the total residual volumeis greater than that of the citric acid, ESO, and shellac—meaning thatsome of the isopropyl alcohol (IPA) is grafted onto the citric acidcapped curative (via an ester linkage). Varying the ratio of IPA toacetone can vary the degree of IPA grafting onto the curative.

Second Illustrative Embodiment and Process for ENR-Based Material

Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100parts of rubber to 30 parts of the curative as prepared in the firstembodiment. In addition, 70 parts of ground cork powder (MF1 fromAmorim) was added as a filler. This mixture was made on a two-rollrubber mill according to normal compounding practices. The mixture wassheeted out and molded at 110° C. for 30 minutes. It was found to beproperly cured, with similar elongation and strain recovery as sulfurand peroxide cure systems.

Third Illustrative Embodiment and Process for ENR-Based Material

Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100parts of rubber to 45 parts of the curative as prepared in the firstembodiment. In addition, 70 parts of ground cork powder (MF1 fromAmorim) was added as a filler. This mixture was made on a two-rollrubber mill according to normal compounding practices. The mixture wassheeted out and molded at 110° C. for 30 minutes. It was found to befully cured, but with some attributes of over-crosslinked systems;including lower tear resistance and very high resilience.

Fourth Illustrative Embodiment and Process for ENR-Based Material

Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100parts of rubber to 15 parts of the curative as prepared in the firstembodiment. In addition, 70 parts of ground cork powder (MF1 fromAmorim) was added as a filler. This mixture was made on a two-rollrubber mill according to normal compounding practices. The mixture wassheeted out and molded at 110° C. for 30 minutes. It was found to becured, but with a relatively low state-of-cure; with attributes such aslow resilience and poor strain recovery.

Fifth Illustrative Embodiment and Process for ENR-Based Material

Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100parts of rubber to 30 parts of the curative as prepared in the firstembodiment. In addition, 70 parts of ground cork powder (MF1 fromAmorim) was added as a filler. Additionally, 20 parts of garneted fiber(from recovered textiles) was added. This mixture was made on a two-rollrubber mill according to normal compounding practices. The mixture wassheeted out and molded at 110° C. for 30 minutes. It was found to befully cured and additionally had a relatively high extensional modulusin accordance with the fiber content.

Sixth Illustrative Embodiment and Process for ENR-Based Material

Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100parts of rubber to 30 parts of the curative as prepared in embodiment 1.In addition, 60 parts of ground cork powder (MF1 from Amorim) was addedas a filler. Additionally, 80 parts of garneted fiber (from recoveredtextiles) was added. This mixture was made on a two-roll rubber millaccording to normal compounding practices. The mixture was sheeted outand molded at 110° C. for 30 minutes. It was found to be fully cured andadditionally had a very high extensional modulus in accordance with thefiber content.

Seventh Illustrative Embodiment and Process for ENR-Based Material

Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100parts of rubber to 60 parts of the curative as prepared in embodiment 1.In addition, 35 parts of ESO was added as a reactive plasticizer. Inaddition, 350 parts of ground cork powder (MF1 from Amorim) was added asa filler. Additionally, 30 parts of garneted fiber (from recoveredtextiles) was added. This mixture was made on a two-roll rubber millaccording to normal compounding practices. The mixture was sheeted outand molded at 110° C. for 30 minutes. It was found to be fully cured,rigid, and additionally had a relatively high extensional modulus inaccordance with the fiber content.

Eighth Illustrative Embodiment and Process for the Creation of Curativethat is Used in the Preparation of ENR-Based Material

Curative was prepared by dissolving 50 parts of citric acid in a warmblend of 110 parts of isopropyl alcohol. After the citric acid wasdissolved, 50 parts of ESO was added to the mixture along with 10 partsof Beeswax. The mixture was heated and stirred continually until all thevolatile solvents had evaporated. The total residual volume is greaterthan that of the citric acid, ESO, and beeswax—meaning that some of theisopropyl alcohol (IPA) is grafted onto the citric acid capped curative(via an ester linkage). The reduced liquid mixture was added to fineprecipitated silica (Ultrasil 7000 from Evonik) to make a 50 wt % dryliquid concentrate (DLC) for easy addition in subsequent processing.

Ninth Illustrative Embodiment and Process for ENR-Based Material

Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100parts of rubber to 50 parts of the curative DLC as prepared in theeighth illustrative embodiment along with 30 additional parts of fineprecipitated silica. It was found that mixing of the curative DLCprepared in eighth illustrative embodiment eliminated some stickiness inprocessing that was experienced when mixing in curative that was notpre-dispersed as a DLC. The resulting mixture was cured in a press atapproximately 50 psi at 110° C. for 30 minutes to make a translucentslab.

The material of this embodiment was found to have attributes that areanalogous to those found in animal-hide leather; including slow recoveryafter folding, vibration damping attributes, and high tear strength. Itis believed that the total silica loading (55 parts) and this particularcurative contribute to the “lossy” characteristics of this material.Without wishing to be bound by theory, it is possible that the level oftotal silica loading is approaching the percolation threshold andcreating particle-particle interactions that are creating the lossyattributes without limitation unless otherwise indicated in thefollowing claims. This is a preferred mechanism to reliance on polymerformulations that experience a T_(g) near room temperature as a means tocreate a lossy material, as such an approach would lead to poor coldcrack resistance.

Tenth Illustrative Embodiment and Process for ENR-Based Material

Epoxidized Natural Rubber with 25% epoxidation (ENR-25) was mixed at 100parts of rubber to 30 parts of so-called “cottonized” hemp fiber, thismixture was mixed on a two-roll mill using a tight nip to get an evendispersion of fiber. To this masterbatch 50 parts of the curative DLC asprepared in the eighth illustrative embodiment along with 30 additionalparts of fine precipitated silica. The resulting mixture was cured in apress at approximately 50 psi at 110° C. for 30 minutes to make atranslucent slab. The material of the tenth illustrative embodiment wasfound to have similar attributes as the material of the ninthillustrative embodiment with the change of having much lower elongationat break and much higher modulus in accordance with the fiber loading.

Eleventh Illustrative Embodiment and Process for ENR-Based Material

A black batch of ENR-based material was prepared by mixing ENR-25 withcoconut charcoal to achieve the desired black color. In addition to theblack colorant, other ingredients were added to yield a processiblebatch of rubber. Other ingredients may include clay, precipitatedsilica, additional epoxidized soybean oil, castor oil, essential oilodorants, tocopheryl (Vitamin E—as a natural antioxidant), and curative.This material was then cured in a tensile-plaque mold at 150° C. for 25minutes to complete the curing.

Twelfth Illustrative Embodiment and Process for ENR-Based Material

A brown batch of ENR-based material was prepared by mixing ENR-25 withcork powder to achieve the desired brown color and texture. In additionto the cork, other ingredients were added to yield a processible batchof rubber. Other ingredients may include clay, precipitated silica,additional epoxidized soybean oil, essential oil odorants, tocopheryl(Vitamin E—as a natural antioxidant), and pre-polymer curative. Thismaterial was then cured in a tensile-plaque mold at 150° C. for 25minutes to complete the curing.

Tensile stress-strain curves are shown in FIG. 9 for materials preparedaccording to the eleventh and twelfth embodiments. It can be seen thatthe cork-filled brown batch (twelfth embodiment) is higher in modulusthan the black batch (eleventh embodiment) for this particular example.In these two illustrative embodiments, the brown batch (twelfthembodiment) had a Shore A hardness of 86 while the black batch (eleventhembodiment) had a Shore A hardness of 79.

The optimal amount of the additional materials may vary according to thespecific application of the ENR-based material, and various ranges forsame are shown in Table 1.

TABLE 1 Acceptable and Preferred Ranges of Other Ingredients. PreferredRange Acceptable Range (Percent of Total (Percent of Total IngredientProduct Weight) Product Weight) ENR-25 40-60  20-90  Curative 2-10 1-50Cork 3-10 0-70 Colorant 0-15 0-50 Precipitated Silica 15-35  0-50 EVO0-10 0-30 Non-reactive vegetable oil 0-10 0-30 Odorant 0.5-3   0-10Vitamin E/antioxidant 0.2-2   0-4  Mineral filler (e.g., clay) 0-15 0-50

Variations in the other ingredients: clay, precipitated silica,additional epoxidized soybean oil, castor oil, and/or amount of curativemay be used to vary the modulus of a batch/recipe within a range that ischaracteristic of traditional rubber recipes. By those well versed inrubber compounding it is recognized that formulations of rubber may beselectively compounded with hardnesses ranging from approximately 50Shore A up to about 90 Shore A. The illustrative formulations show thatthese compounds fall within the range of expected performance forepoxidized natural rubber. Furthermore, it is known that traditionallycompounded natural rubber may achieve strength values from 10-25 MPa.The eleventh illustrative embodiment displays physical properties inline with traditionally compounded natural rubber.

Materials made according to this disclosure may further be reinforcedwith continuous fiber to make stronger products. Methods forreinforcement may include but are not limited to use of both woventextiles, non-woven textiles, unidirectional strands, and pliedunidirectional layers unless otherwise indicated in the followingclaims. Reinforcement may preferably come from natural fibers and yams.Illustrative yarns may include, but are not limited to, cotton, jute,hemp, ramie, sisal, coconut fiber, kapok fiber, silk, or wool andcombinations thereof unless otherwise indicated in the following claims.Regenerated cellulose fibers such as viscose rayon, Modal® (a specifictype of viscose, by Lenzing), Lyocell (also known as Tencel®, byLenzing), or Cuprammonium Rayon may also be used without limitation orrestriction, as suitable for a particular application, unless otherwiseindicated in the following claims. Alternatively, reinforcement mayrequire the strength of synthetic fiber yarns based on para-aramids,meta-aramids, polybenzimidazole, polybenzoxazole, and similar highstrength fibers. In another illustrative embodiment, a reinforcementlayer and/or material may be configured from a protein-based fiber,which fibers include but are not limited to of wool, silk, alpaca fiber,qiviut, vicuna fiber, llama wool, cashmere, and angora unless otherwiseindicated in the following claims. Illustrative natural yarns maybeneficially be treated by the natural fiber welding process to improvetheir strength, reduce their cross-sectional diameter, and improvefiber-to-elastomer bonding characteristics. Such yarns may be plied intothreads that provide interpenetration features between reinforcement andelastomer as well as improve the strength of the reinforcement. Forcertain applications it may be preferred to provide reinforcement byunidirectional reinforcement in plied layers as compared to woven andknit reinforcement. It has been found that such woven and knitreinforcement may improve product stiffness but may negatively impacttear strength by creating stress-concentration features around yams andfibers. In contrast, unidirectional reinforcement at various ply anglesmay avoid such stress concentrating features. In a related way,non-woven mats may be used as reinforcement as they do not containregularly oriented stress-concentrating features but do enable longreinforcement fiber lengths at high fiber volume fractions. In a relatedway, integrally mixed fiber content has been found to improve stiffnessbut decrease tear strength at certain volume and weight fractions. Tearstrength improvement is observed when total fiber content exceeds 50 phr(in traditional rubber compounding nomenclature), especially with evendispersion and good retention of fiber length during processing.

Molding and curing of materials according to the present disclosure hasbeen found to require only modest pressure to achieve porosity-freearticles. While traditional rubber cure systems evolve gasses and thusrequire molding pressures generally greater than 500 psi and oftencloser to 2000 psi, the compounds disclosed herein only require moldingpressure of 20 psi-100 psi, or more specifically 40 psi-80 psi toachieve consolidation and porosity-free articles. The actual requiredpressure may be dependent more on the amount of material flow and detailrequired in the final article. Such low molding pressures allow theusage of much lower tonnage presses that are correspondingly lessexpensive. Such pressures also allow much less expensive tooling; evenembossed texture papers have been found to create suitable patterns inelastomeric materials made according to this disclosure and such texturepapers are found to be reusable for multiple cycles without loss ofpattern detail. The material edge strength has been found to be adequateeven when using open-sided tooling—this allows for faster tool cleaningand significantly reduced tooling costs.

The low molding pressures further allow for such elastomeric materialsto be molded directly onto the surface of resilient and porous coresubstrates. For example, the material may be overmolded onto non-woveninsulative mats as a resilient flooring product or automotive interiorproduct that exhibits soft-touch and sound absorption characteristics.Similarly, the product may be overmolded onto softwoods or similar lowcompressive strength substrates without damage to the substrate.

As previously described, certain catalysts are known in the art to speedup the carboxylic acid addition to epoxide groups and such may be usedin formulating recipes according to the present disclosure withoutlimitation unless otherwise indicated in the following claims.

Animal-hide leather has distinctive characteristics in terms ofelongation, resiliency, loss modulus, and stiffness that are differentthan a regularly compounded elastomer. In particular, animal-hideleather may be folded back on itself without cracking—largelyindependent of temperature. That is, it does not have a material phasethat becomes brittle at low temperatures. Animal-hide leather also hasvibration damping characteristics that are less common with regularlycompounded elastomeric compounds. Animal-hide leather has slow recoveryafter creasing or folding, but does generally recover completely withminimal plastic deformation. These attributes may be mimicked inmaterials compounded according to the present disclosure in theillustrative embodiments and methods for same disclosed herein.

C. Additional Treatments

Articles produced according to this disclosure may be finished by anymeans known in the art. Such means include but are not limited toembossing, branding, sanding, abrading, polishing, calendering,varnishing, waxing, dyeing, pigmenting, and the like unless otherwiseindicated in the following claims. Such articles may be configured toexhibit characteristics very analogous to animal-hide leather. Thesurfaces then may be treated with natural oil or wax protectants,subject to a particular application.

D. Applications/Additional Illustrative Products

Articles molded with materials according to this disclosure may be usedas plant-based alternatives to petrochemical-based leather-like productsand/or animal-hide leather products. In one illustrative embodiment thearticles may be molded substantially as sheets with various texturesaccording to the desired application. The sheets may be used in durablegoods such as upholstery, seating, belts, shoes, handbags, purses,backpacks, straps, equestrian gear, wallets, cellular phone cases, andsimilar articles without limitation unless otherwise indicated in thefollowing claims. Alternatively, such materials may be molded directlyto the shape of the final article in applications such as shoe soles,shoe toes, shoe heal cups, shoe uppers, purses, horse saddles and saddlecomponents, helmet coverings, chair armrests, and similar articles.

Materials according to this disclosure may be overmolded onto resilientmaterials and thus be used as flooring, exercise mats, or soundabsorption panels. Similarly, those materials could be overmolded ontogarments as, for example, a knee patch or elbow patch for improvedabrasion resistance for a region of a garment. Likewise, motorcyclegarments (e.g., chaps) and equestrian gear may be overmolded ofmaterials according to this disclosure to provide improved localabrasion resistance and protection.

Materials according to this disclosure may be molded into complexthree-dimensional articles and multi-laminated articles. That is,certain formulations according to this disclosure may provide improvedtear strength, while other formulations according to this disclosure mayprovide improved abrasion resistance. Such formulations may be laminatedand co-molded to provide articles with improved overall performancecompared with an article made of only one formulation. Three-dimensionalarticles may be molded to provide additional product features,attachment points, and other functionality without limitation unlessotherwise indicated in the following claims. Three-dimensional articlesmay also consist of multiple formulations arranged at various locationswithin an article to provide functionality required for each location.

One example of such molded-in functionality is shown in FIGS. 10A & 10B,which provides a perspective view of a portion of a belt made of anENR-based material. Specifically, in FIG. 10A, a tapered feature (shownon the right-hand side of FIG. 10A) may be molded into a sheet that islater slit into belt sections. The reduced thickness (which may be dueto the absence of a backing material/backing layer (e.g., non-woven mat)in the area having reduced thickness) allows for a folded buckleretention area that is substantially similar in thickness to beltsections that are not folded over on itself, which is shown in FIG. 10Bwhere the reduced-thickness area has been engaged with a buckle.Additionally, the region that is folded back onto itself may bepreferentially bonded in place with additional resin or ENR-basedmaterial molded between the folded region with a cure cycle that issimilar to that used during the initial molding of the sheet.

Shown in FIG. 11 are a series of retention grooves and ridges that maybe molded into the end of the belt to provide a friction-based retentionfeature. That is, some belts made with woven nylon or other textiles aretightened and retained on the wearer by friction between ribs woven intothe belt and a metal bar used in the clasp. Such features may beadvantageous in that they prevent stress risers from developing aroundpunched holes used for retention in common belt buckles. Retentiongrooves & ridges and/or other features for retaining the position of aportion of a belt easily molded into a belt sheet by the creation ofmatching features in the mold tooling (which may be silicone or metal)when making an ENR-based material according to the present disclosure.

ENR-based materials configured for use as a belt may be made in sheetsand may be produced by molding according to the pattern illustrated inFIG. 12. As shown in FIG. 12, the sheet may be comprised of variouslayers, wherein each outside layer of the sheet may be comprised of anENR-based material (e.g., “sheeted rubber preform” in FIG. 12) with oneor more fibrous backing materials/backing layers positionedtherebetween. The backing materials may be comprised of a wovenreinforcement or a non-woven mat in the illustrative embodiment shown inFIG. 12, but any suitable backing material/backing layer may be usedwithout limitation unless otherwise indicated in the following claims.At least one of the backing materials may be a coated fabric (as shownin FIG. 12 for the layer labeled “non-woven mat”), which may beconstructed in accordance with Section 2 described herein above. Texturepaper may be positioned adjacent one or both ENR-based material layersto provide the desired aesthetics to the outer layers of the sheet andresulting article. Finally, a silicone release sheet may be positionedadjacent one or both texture papers for ease of use.

It has been found that the relatively low required pressure to yield aproperly cured specimen utilizing ENR-based materials allows for the useof low-cost paper and silicone tooling. So-called texture papers areused in polyurethane and vinyl leather alternatives to achieve thedesired texture. It has been found that these texture papers likewiseare effective in creating patterns in ENR-based materials as disclosedherein. An advantageous molding configuration is shown in FIG. 12,wherein release silicone sheets are provided as the top-most andbottom-most layers in the sandwich that is molded under temperature andpressure. If the “outside” faces of the belt are desired to be textured,texture paper may be provided next to the silicone sheets. These mayadvantageously be treated with a release aid to promote easy release andreuse of the texture paper. Silicone and vegetable oil have both beenfound to be effective in release and reuse of the texture paper but anysuitable release agent may be used without limitation unless otherwiseindicated in the following claims.

The uncured rubber pre-form sheets may be loaded into the sandwich nextto the texture paper(s). Between the rubber pre-form sheets a non-wovenmat and/or woven reinforcement layer(s) may be provided. In oneillustrative embodiment, the non-woven mat may comprise recycledtextiles, hemp fibers, coconut coir fibers, or other environmentallybenign (biodegradable) fibers, and/or combinations thereof withoutlimitation unless otherwise indicated in the following claims. In oneillustrative embodiment the woven reinforcement layer may comprise juteburlap or similar open-structure woven product that is high in strengthand biodegradable. In another illustrative embodiment so-called cottonmonk's cloth may be also used as a woven reinforcement layer withoutrestriction unless otherwise indicated in the following claims. In someconfigurations open-structure woven products provide relatively goodtear strength when compared to tight woven fabrics. In anotherillustrative embodiment, a reinforcement layer (woven or non-woven) maybe configured from a protein-based fiber, which fibers include but arenot limited to of wool, silk, alpaca fiber, qiviut, vicuna fiber, llamawool, cashmere, and angora unless otherwise indicated in the followingclaims.

ENR-based materials configured for use as leather substitutes may beused in applications where animal-hide leather is used today. Suchapplications may include belts, purses, backpacks, shoes, table tops,seating, and the like without limitation unless otherwise indicated inthe following claims. Many of these articles are consumable items thatif made from petrochemical-based leather-like products arenon-biodegradable and are non-recyclable. If such items are made fromthe material disclosed herein, they would be biodegradable and thus notcreate a disposal problem. Furthermore, unlike animal-hide leather,which requires significant processing to be made durable and stable(some of which uses toxic chemicals), the materials disclosed herein mayrequire less processing and will use environmentally friendly chemicals.Additionally, animal-hide leather is limited in size and may containdefects that render large pieces inefficient to produce. The materialdisclosed in at least one embodiment herein does not have the same kindof size limitations as the reaction between epoxide groups andcarboxylic groups does not create any condensation by-products, there isno inherent limit to the cross-sectional thickness that may be created.

4. Mechano-chemically Modified Thermoset Material

A. Background

Leather-like materials based on synthetic polymers such as polyurethane(PU) and polyvinyl chloride (PVC) are well known in the art. Thesematerials have been formulated to have haptics that mimic, in many ways,the feel of animal leather. Animal leather is a collagen-based structurethat is usually filled with waxes and oils that impart both softness anda slick surface—termed “buttery” by those in the art. PVC, for example,may achieve similar haptics by the combination of the polymer itselfthat may have a glass transition temperature, Tg, above room temperaturecombined with plasticizers that drop the bulk material stiffness so thatit remains flexible well below room temperature. PU, in another example,may achieve similar haptics by the combination of so-called hard blockdomains (with a Tg above room temperature) and soft block domains (witha Tg below room temperature) synthesized into the polymer backbone. Inthese examples, there is a phase or constituent with a Tg above roomtemperature (collagen, PVC polymer, and PU hard blocks) and a phase orconstituent with a Tg below room temperature (tanning agents and oilsfor animal leather, plasticizers for PVC, and soft block domains forPU). This combination of phases or constituents that have a Tg aboveroom temperature and phases or constituents with a Tg below roomtemperature and may yield a favorable haptic combining softness of thebulk article without imparting a “grippy” surface.

Materials based on natural rubber or other related polymers, such asepoxidized natural rubber, tend to have a polymer phase with a single Tgthat is below room temperature; thus compounds based on natural rubber(NR) or epoxidized natural rubber (ENR) tend to have a “grippy” surfacethat is undesirable when developing a leather-alternative material. Itwould be desirable to combine the beneficial low temperature flexibilityand softness that comes from NR or ENR with a slick or buttery surfacehaptic for the creation of a leather-alternative material.

B. Summary

Disclosed is a combination of a plant-based all-natural polymer that canbe combined with ENR to yield a polymeric mixture that maintains theexcellent low temperature flexibility of the ENR while delivering thehaptics associated with a polymer having a Tg nearer room temperature.

In another embodiment, disclosed is a combination of a plant-basedall-natural polymer that can be combined with ENR and another optionalplasticizer that further suppresses the glass transition temperature toimpart excellent low temperature flexibility (down to −10° C. or lower).

Disclosed is an illustrative method of selectively reversing covalentchemical crosslinks (which reversing may also referred to herein as“de-crosslinking”) in a thermoset material through mechano-chemicalprocessing using low temperature (e.g., less than 70° C.) and highshear, which may be performed by passing a thermoset material repeatedlythrough a narrow gap (<1 mm) of a two-roll rubber mill (approximately1.25:1 friction ratio) or through mixing in an internal mixer. Themethod has been found to cause scission primarily to crosslinks topartially reverse the cure. Such mechano-chemically modified thermosetmay be used as one constituent in a mixture with ENR to yield aleather-like alternative material with improved haptics.

As used herein, the term “thermoset material” is meant to include allthermosets without limitation unless otherwise indicated in thefollowing claims, including those thermosets that are made via resin(liquid) precursors, gum precursors, semi-solid precursors,thermoplastic precursors, and/or combinations thereof.

Various methods exist for determining the power-per-unit-volume ofthermoset material required to selectively break the crosslinks in thethermoset material disclosed herein, and the scope of the presentdisclosure is in way limited by a specific method for determining sameunless otherwise indicated in the following claims. In one illustrativemethod for determining the aforementioned power-per-unit-volume ofthermoset material, the thermoset material may be mixed on a two-rollmill with a nip gap of 0.5 mm. The power consumption may beapproximately 5000 W (5 kW). As the thermoset material fills the nipwidth of 30 cm, it may be assumed that the majority of power input intothe thermoset material happens below a nip gap of 1.5 mm becauseexperiments show very little mechano-chemical de-crosslinking at thisnip gap or larger. For mills configured with rolls with a radius of 75mm (6-inch rolls), this corresponds to an arc of approximately 13°(+/−6.5° around the point of closest approach). One may accordinglyestimate that the volume of material within this nip gap across thewidth of the mill is approximately 7.5 ml. Therefore, a reasonableestimate of the instantaneous power input to enable mechano-chemicalde-crosslinking is 5000 W/0.0075 liters=6.67×10⁵ W/l.

However, in some instances, the power consumption on the two-roll millmay be as low as 2000 W (2 kW). The mill geometry and nip gap remain thesame and the mill width remains the same. In these instances, theinstantaneous power input to enable mechano-chemical de-crosslinking maybe 2000 W/0.0075 liters=2.67×10⁵ W/l.

Through experimentation, the lowest shear variation that has beenobserved to selectively de-crosslink the thermoset material through amechano-chemical process mechano-chemical de-crosslinking may occur witha minimum nip gap of 0.8 mm with an estimated power consumption of 2000W (2 kW). In this instance, the estimated volume of thermoset materialexperiencing the high shear near the nip may be as much as approximately10 ml. In this example, the instantaneous power input to enablemechano-chemical de-crosslinking may be 2000 W/0.01 liters=2×10⁵ W/l.

In the preceding illustrative embodiments, the mechano-chemicalde-crosslinking may be characterized by very high instantaneouspower-per-volume shear mixing followed by periods of cooling so that thetemperature of the thermoset material that is being mixed never exceedsapproximately 70° C. (above which temperature the thermoset material maybegin re-curing, that is, re-crosslinking). On a two-roll mill, thehigh-shear mixing zone has been estimated to be happening over an arclength of approximately 13°, thus by deduction the estimated low-shearor no-shear cooling time occurs during the remaining periphery of theroll (i.e., the remaining approximately 347° of travel). Accordingly,the high shear time may be experienced by the thermoset material forapproximately 13/360, or 3.6% of the total mixing time. In this way, themaximum material temperature may be limited, despite havinginstantaneous times of very high-power input (per volume).

Disclosed is a reaction product between an epoxidized plant-sourcedtriglyceride (an example of which may be epoxidized soybean oil (ESO))and a naturally occurring polyfunctional carboxylic acid (an example ofwhich may be citric acid) wherein the thermoset reaction productcontains β-hydroxyesters as the linkages between the epoxidizedplant-sourced triglyceride and the naturally occurring polyfunctionalcarboxylic acid. It has been unexpectedly discovered that theβ-hydroxyester linkages may be selectively and reversibly broken bymechanical shear only. That is, the thermoset matrix sourced from smalland highly branched precursor molecules may be transformed into amillable gum by the action of high-shear mixing. Such mechanicallymasticized thermoset has been found to be capable of being re-cured intoa thermoset by the re-application of heat without the addition ofadditional curative functionality (that is, without the addition ofvirgin epoxidized plant-sourced triglyceride or carboxylic-acidfunctionality).

Disclosed is an epoxidized natural rubber that is crosslinked by acarboxylic-acid containing curative. Crosslinks between the epoxidegroups and the carboxylic-acid curative form β-hydroxyesters. Suchβ-hydroxyesters are known to be capable of thermally-inducedtransesterification reactions. Such reactions have been used to makeso-called “self-healing” and recyclable thermosets.¹ In the prior art,it has been assumed that transesterification reactions proceed in a sortof zero-sum rearrangement where the total number of linkages isgenerally stable, Leibler et. al states, “The underlying concept is toallow for reversible exchange reactions by transesterification thatrearrange the network topology while keeping constant the total numberof links and the average functionality of cross-links.”² ¹“Self-healable polymer networks based on the cross-linking of epoxidizedsoybean oil by an aqueous citric acid solution”, Facundo I. Altuna,Valeria Pettarin, Roberto J. J. Williams, Green Chem., 2013, 15,3360²“Silica-Like Malleable Materials from Permanent Organic Networks”,D. Montarnal, M. Capelot, F. Tournilhac and L. Leibler, Science, 2011,334, 965-968.

It has been unexpectedly discovered that by pairing a high molecularweight polymer based on a carbon-carbon backbone with crosslinks ofβ-hydroxyesters, the crosslinks may be selectively and reversibly brokenby mechanical shear only. That is, a high molecular weight elastomersuch as epoxidized natural rubber that has been crosslinked (vulcanized)through β-hydroxyesters may be mechanically processed by very high shearsuch that the high molecular weight linear rubber may be substantiallyretained while the crosslinks are selectively broken in such a way thattheir initial functionality is regenerated. The resultant re-milledrubber may be re-molded without the addition of additionalcurative—demonstrating that the curative is not only selectively broken,but also that the carboxylic-acid functionality and epoxidefunctionality are regenerated during the breaking of the crosslinks.Such mechanically induced regeneration of curative functionality has notbefore been disclosed.

Disclosed is the combination of virgin epoxidized natural rubber andmechanically masticized thermoset material (which may be configured as athermoset resin) that was formed as the reaction product between anepoxidized plant-sourced triglyceride and a naturally occurringpolyfunctional carboxylic acid. Such reaction product may be preferablyproduced according to the methods disclosed Section 2—Coated Fabrics,though the scope thereof is not so limited unless otherwise indicated inthe following claims. The mechanically masticized thermoset material mayfunction as the curative for the virgin epoxidized natural rubber. Suchmechanical masticization of the thermoset material and mixing of therecipe has been found to be able to occur concurrently.

C. Detailed Description

Thermoset materials (and specifically, thermoset resins) and thermosetelastomers are well known in the art. In most cases, the covalent bondsformed between molecules have strength characteristics that arecommensurate with the strength characteristics within the precursormolecules. In such materials, mechanical shear results in turning thethermoset material into a granule or powder that may be used as a fillerin new materials, but is not capable of returning the thermoset materialinto a high molecular weight gum, having characteristics substantiallythe same or even similar to the starting precursor material(s). Someionically crosslinked materials, when formed by the coordination ofcharges along the polymer backbone, may be made to flow under eitherhigh shear or the application of very high temperatures, but this typeof reversible thermoset behavior is not known among covalently bondedthermoset materials.

It is known in the art that crosslinks between the epoxide groups and acarboxylic-acid curative form β-hydroxyesters. Such β-hydroxyesters areknown to be capable of thermally induced transesterification reactions.Such reactions have been used to make so-called “self-healing” andrecyclable thermosets. In the prior art, it has been assumed thattransesterification reactions proceed in a sort of zero-sumrearrangement where the total number of linkages is generally stable,Leibler et. al states “The underlying concept is to allow for reversibleexchange reactions by transesterification that rearrange the networktopology while keeping constant the total number of links and theaverage functionality of cross-links.”

It has been unexpectedly discovered that β-hydroxyester crosslinks maybe selectively and reversibly broken (i.e., de-crosslinked) bymechanical shear only. That is, a thermoset material with linkages thatare β-hydroxyesters, as shown in the cured thermoset resin of FIG. 13(wherein small arrows on the right side of the figure show reactivesites in for the compound), may be mechanically processed by very highshear such that the thermoset material may be masticized as thecrosslinks are selectively broken in such a way that their initialfunctionality is regenerated. The resultant masticized thermoset may bere-cured without additional curative—demonstrating that the curative isnot only selectively broken, but also that the carboxylic-acidfunctionality and epoxide functionality are regenerated during thebreaking of the crosslinks as shown in FIG. 15. Such mechanicallyinduced regeneration of curative functionality has not before beendisclosed.

i. Regenerated Thermoset Materials Based on Epoxidized Natural Rubber

It has been unexpectedly discovered that by pairing a high molecularweight polymer based on a carbon-carbon backbone (such as epoxidizednatural rubber) with crosslinks of β-hydroxyesters, the crosslinks areselectively and reversibly broken by mechanical shear only. That is, ahigh molecular weight elastomer such as epoxidized natural rubber thathas been crosslinked (vulcanized) through β-hydroxyesters may bemechanically processed by very high shear such that the high molecularweight linear rubber may be substantially retained while the crosslinksare selectively broken in such a way that their initial functionality isregenerated. The resultant re-milled rubber, which has beende-crosslinked (also called devulcanized), may be re-molded withoutadditional curative—demonstrating that the curative is not onlyselectively broken, but also that the carboxylic-acid functionality andepoxide functionality are regenerated during the breaking of thecrosslinks. Such mechanically induced regeneration of curativefunctionality has not before been disclosed.

A rubber compound of epoxidized natural rubber (ENR-25) and acarboxylic-acid functional curative as disclosed in Section 1 above maybe mixed with additional fillers and additives as may be common in theart. In one illustrative embodiment, the compound contains powdered corkand precipitated silica. A series of rheometer traces is shown in FIG.16 from a moving die rheometer (MDR) as measured at 150° C. for 30minutes. The initial trace shows a characteristic cure curve with abrief induction time and then marching modulus for the 30-minute cure.The rheometer sample was then subject to remilling on a lab-scale (6″diameter×12″ wide) two-roll rubber mill. After a few passes through themill wherein the sample exhibited nervy behavior, it gradually becameflowable in a similar way to uncured rubber under continued mixing. Thesecond rheometer curve (“second trace” on FIG. 16) on this particularsample shows a higher initial modulus but thereafter cures to roughlythe same final stiffness at a similar rate. This particular sample ofmaterial was subsequently remilled again and cured again. This wasrepeated eleven times—the sixth and eleventh cure traces are shown inFIG. 16. It can be seen that the general shape of the cure curve issimilar for all re-curing experiments; the modulus drops as the numberof recycling loops increases, but each time, the sample was shown to becapable of re-curing without the addition of more curative. The twelfthcure curve (“twelfth trace, added curative” on FIG. 16) reflects theaddition of a small amount of curative that was able to increase themodulus of the sample.

The series of cure curves of FIG. 16 shows that the compound may bede-crosslinked by the application of mechanical shear only—without theaddition of heat (that is, the rolls of the two-roll mill were notheated for any of these experiments). Furthermore, the rheometer tracesshow that the curative is capable of re-crosslinking the epoxidizednatural rubber after mechanical de-crosslinking. In contrast to priorliterature on transesterification, it has been shown that the totalnumber of crosslinks do not need to be maintained to regenerate solidmaterials with mechanical integrity. The curative may regenerate itselfafter being sheared apart by mechanical forces.

In another set of experiments, the same recipe that was used in FIG. 16was subject to rheometry at a series of increasing temperatures. Thisdata is shown in FIG. 17 for the temperatures of 150° C., 175° C., 200°C., and 225° C. It can be seen that the state of cure increases withincreasing temperature to 200° C. There is some small evidence ofreversion at 200° C. At 225° C., we see an initial cure that is followedby rapid reversion that is nearly complete at the end of the 30-minutetest. This is evidence that the crosslinking bonds are substantiallyweaker than the epoxidized natural rubber itself, which has an onset ofthermo-oxidation at approximately 250° C. Therefore, we may surmise thatmechanical stresses are capable of breaking the weaker subset ofcovalent bonds—in this case, the β-hydroxyester crosslinks.

ii. Regenerated Thermoset Materials based on Epoxidized Plant Oil andNaturally Occurring Polyfunctional Acid

It has been unexpectedly discovered that the reaction product of twosmall molecules (such as epoxidized soybean oil (ESO) and citric acid),wherein the covalent linkages between the molecules of the thermosetmaterial (which for this illustrative embodiment is configured as athermoset resin) are β-hydroxyesters, may be transformed into a millablegum by mechanical shear only. That is, a highly branched elastomer maybe transformed into a more linear and extensible material through thereversible fracture of a subset of the β-hydroxyester covalent linkagesas shown in FIG. 15. This millable gum may furthermore be usedadvantageously in two or more ways. In one preferred illustrativeembodiment, the millable gum may be subsequently combined with anynumber of fillers, plasticizers, or functional additives and thenre-cured—without the addition of additional epoxidized plant-sourcedtriglyceride (such as ESO) or naturally occurring polyfunctionalcarboxylic acid (such as citric acid). In another preferred illustrativeembodiment, the millable gum may be sheeted out without combination withadditional fillers, plasticizers, or functional additives and thenre-cured as a transparent film (either by itself or in contact withbacking fabric or other backing material). In another preferredillustrative embodiment, the millable gum may be subsequently combinedwith virgin epoxidized natural rubber wherein the epoxidized naturalrubber is crosslinked through the action of the regenerated carboxylicacid functionality that was achieved through the mechanical shear of thethermoset material.

By way of illustration, and without limitation unless so indicated inthe following claims, various processes and parameters thereof aredescribed in detail below. The values for the parameters given below arefor illustrative purposes only and are in no way limiting unlessotherwise indicated in the following claims. Other parameter values,methods, equipment, etc. may be used without limitation unless otherwiseindicated in the following claims.

Example 1

100 parts of Citric Acid, 100 parts of ESO, and 400 parts of IsopropylAlcohol (IPA) are charged into a vacuum-capable reactor vessel. Themixture is slowly heated over the course of 8 hours with constantstirring and under modest vacuum (>50 Torr). The IPA is condensed duringthe reaction period and removed from the solution. At the end of thereaction period, when substantially all of the unbound and unreacted IPAis removed, the temperature of the reactor vessel rises quickly and thereaction is halted when the reaction product reaches 110° C.

Example 2

109 parts of the reaction product of Example 1 is mixed with 100 partsof ESO to yield a curable resin. This resin may be cured overnight at80° C. or within two hours at 125° C. to make an elastomeric solid.

Example 3

The cured elastomeric solid of Example 2 is passed repeatedly through atight nip on a rubber mill. The friction ratio is 1.25:1 and the nip isset to less than 0.5 mm. After a few passes, the powdery material beginsto masticate and within about 3-7 minutes of mixing a millable gum isgenerated. This millable gum may be sheeted out and re-cured as atransparent sheet or it may be combined with fillers, plasticizers,and/or functional additives to yield a compound that may be cured underheat (e.g. 150° C. for 5 minutes) to make a thermoset elastomer. Themillable gum may be combined with epoxidized natural rubber (ENR) andENR-based compounds and act as a curative for the ENR.

Example 4

109 parts of the reaction product of Example 1 is mixed with 100 partsof ESO along with 7 parts of propylene glycol and 3.5 parts ofolive-derived emulsifying wax to yield a curable resin. This resin maybe cured overnight at 80° C. or within two hours at 125° C. to make anelastomeric solid.

Example 5

The cured elastomeric solid of Example 4 is passed repeatedly through atight nip on a rubber mill. The friction ratio is 1.25:1 and the nip isset to less than 1 mm. After a few passes, the powdery material beginsto masticate and within about 3-7 minutes of mixing a millable gum isgenerated. This millable gum may be sheeted out and re-cured as atransparent sheet or it may be combined with fillers, plasticizers,and/or functional additives to yield a compound that may be cured underheat (e.g. 150° C. for 5 minutes) to make a thermoset elastomer. Thematerial of example 5 is more easily masticated than the material ofexample 3. The millable gum may be combined with epoxidized naturalrubber (ENR) and ENR-based compounds and act as a curative for the ENR.

iii. Thermoset Material Blends Based on Virgin ENR and RegeneratedThermoset Materials Based on Epoxidized Plant Oil and Naturally OccuringPolyfunctional Acid

By combining the technology of mechano-chemically regenerated thermosetmaterials (where such materials have been found to regenerate theoriginal chemical functionality of epoxide groups and carboxylic acidgroups) with virgin ENR, the regenerated functionality is able to cure(i.e., crosslink) the epoxide groups in the ENR without the addition ofadditional curative. This is laid out in the following examples.

Example 6

40 parts of ENR-50 is mixed with 63 parts of the cured resin of Example4 in the previous section. It has been found that there is sufficientshear during the mixing of the ENR-50 with the cured resin of Example 4that the cured resin is mechano-chemically broken down (de-crosslinked)and thus becomes a source of carboxylic acid functionality that iscapable of curing the ENR-50. This mixture of elastomeric gum materialsmay be further combined with fillers, plasticizers, and functionaladditives to yield a compound that may then be cured as an elastomericsolid. In one illustrative embodiment, the fillers may include corkpowder, ground rice hulls, activated carbon, activated charcoal, kaolinclay, metakaolin clay, precipitated silica, talc, mica, corn starch,mineral pigments, and/or various combinations thereof without limitationunless otherwise indicated in the following claims; the plasticizers mayinclude both reactive plasticizers such as epoxidized soybean oil,semi-reactive plasticizers such as glycerol, propylene glycol, andcastor oil, and non-reactive plasticizers such as naturally occurringtriglyceride plant-based oils and/or various combinations thereofwithout limitation unless otherwise indicated in the following claims;the functional additives may include antioxidants (such as tocopherolacetate (Vitamin E)), UV absorbers (such as sub-micron TiO₂),antiozonants, cure retarders (such as alkali sodium salts and powderedsoda glass), cure accelerators (such a certain zinc chelates), and/orcombinations thereof without limitation unless otherwise indicated inthe following claims. Materials made by such processing steps and withsuch ingredients have been found to have excellent flexibility down to−10° C. and buttery haptics.

Example 7

80 parts of ENR-50 is mixed with 21 parts of the cured resin of Example4 in the previous section. It has been found that there is sufficientshear during the mixing of the ENR-50 with the cured resin of Example 4that the cured resin is mechano-chemically broken down (de-crosslinked)and thus becomes a source of carboxylic acid functionality that iscapable of curing the ENR-50. This mixture of elastomeric gum materialsmay be further combined with fillers, plasticizers, and functionaladditives to yield a compound that may then be cured as an elastomericsolid.

The molded materials produced according to Example 6 and Example 7 haveattributes that allow them to be used as leather-substitute materials.The blend of a relatively low Tg materials such as ENR-50 with arelatively higher Tg material such as the masticized resin yields a bulkmaterial with excellent haptics and low temperature flexibility down toat least −10° C. Furthermore, the bulk material glass transitiontemperature can be lowered by incorporating a plasticizer such aspropylene glycol without negatively impacting the tactile properties ofthe material. Instead, it has been found that a plasticizer such aspropylene glycol (which can be made with a catalytic process known ashydrogenolysis to readily convert plant-sourced glycerin and hydrogen topropylene glycol) acts as both a plasticizer and aid to the creation of“buttery” haptics by lowering the surface friction.

In these examples, it has been found that the combination of highmolecular weight ENR and masticized resin yields an optimal balance ofgreen strength, low temperature flexibility, and room temperatureflexibility. Without wishing to be bound by theory, it is believed thatthere may exist domains within the final compound that remain rich inthe resin-based starting thermoset and domains that are more rich inENR. The mixture of domains may limit the localized extensibility of thecompound, thus reducing the sensation of grippiness. In support of thistheory, remilled resin as illustrated in FIG. 15 was stirred intoethanol overnight; the resultant solution showed some small curdledmaterial in the bottom of the container that would not dissolve. Thissuggests that during the remilling operation, a portion of the thermosetmaterial is mechano-chemically modified through shear and once the sheardrops below a certain threshold, the remaining thermoset material doesnot experience sufficient shear to break the β-hydroxyester crosslinks.Therefore, the de-crosslinking is not homogeneously distributedthroughout the material; i.e. some crosslinked domains survive theremilling process. As a result, the combined ENR and remilled resincompound will have some portion of previously crosslinked resin thatsurvive the mixing process and act as domains that impart a locallyhigher Tg and thus less grippy haptic.

5. Applicability

The recycling of thermoset materials is a particularly challengingproblem for the polymer-materials industry. Some proposed solutions forthis challenge have included solvent-induced depolymerization, grindingof waste and re-integration with new binder, and thermaldepolymerization. None of these solutions are easy to integrate intoexisting manufacturing processes. In contrast, the mechanically inducedde-crosslinking of the thermoset material according to this disclosureutilizes the very same equipment and methodology used to mix thematerial in the first place. Thereby, an article may be molded using lowpercentages of reclaimed material all the way up to 100% reclaimedmaterial. Such materials may be utilized in articles substantiallyidentical to articles manufactured with virgin material.

In the manufacturing of leather-like materials, it has beenadvantageously found that the inclusion of at least some reclaimed andrecycled material results in a sheet product having a naturallyoccurring texture that is particularly pleasing—having surfaceundulations on the scale of 1-10 mm that do not require any texture inthe mold. Such surface undulations may be similar to that exhibited bybison or buffalo leather products and is highly desirable for manyapplications.

The ability to integrate waste material (e.g., product trimming, flawedarticles, articles that have reached the end of their useful life, etc.)into articles without significant loss of mechanical properties andwithout the requirement of additional virgin material addition enablesclosed-loop manufacturing in a way not previously envisioned forthermoset materials. Importantly, such materials may be stillbiodegradable and may be sourced from plant-based raw ingredientswithout the inclusion of petrochemically derived precursors.

The use of pre-cured thermoset material as a curative for ENR isparticularly advantageous from a processing standpoint. It has beenfound that the curative as disclosed in Section 1 and then applied inSection 3 may impart stickiness to some of the compounds, especiallyduring mixing. The use of pre-cured themoset resin as disclosed hereinsignificantly reduces the stickiness of the batch during processing andlikewise reduces the tackiness/grippiness of the molded article.

5. Foam Material

A. Background

Most resilient foam products that are commercially available are basedon synthetic polymers, specifically polyurethane. A key attribute thatdifferentiates so-called memory foam from other foam products is theglass transition temperature (T_(g)) of the polymer. Rigid foams aregenerally comprised of polymers with a T_(g) well above roomtemperature, an illustrative example of such a product is polystyrenefoam (often used in rigid insulation boards and insulated drinkingcups). Flexible and springy foams are generally comprised of polymerswith a T_(g) well below room temperature, an exemplary example of such aproduct is a car door weather seal based on ethylene-propylene rubber(EPR/EPDM). Natural products may be likewise found in both rigid andflexible/springy categories. Balsa wood is a generally porous andfoam-like material that is substantially rigid at room temperature.Natural rubber latex may be foamed by either the Talalay or Dunlopprocess to make a flexible and springy foam product that issubstantially comprised of naturally-occurring polymers. To date, thereis no widespread naturally occurring foam that has a T_(g) near roomtemperature to yield a lossy foam that is the key attribute of memoryfoam materials.

Natural materials that make flexible foam products today are often basedon natural rubber latex. To make latex products stable to temperatureexcursions, the polymer must be vulcanized (i.e., crosslinked).Vulcanization of natural rubber may occur through a few known methods;most often sulfur vulcanization may be used, but peroxide or phenoliccure systems may likewise be used. Although sulfur and zinc oxide curesystems may be capable of vulcanizing natural rubber latex, very oftenother chemicals are added to increase the cure rate, limit reversion,and provide other functional benefits (e.g., anti-oxidants,anti-ozonates, and/or UV stabilizers). These additional chemicals maycreate chemical sensitivities in certain individuals. Also, naturalrubber latex itself may cause allergic reactions in certain individualsdue to the natural proteins that exist in the latex.

Similar natural rubber latex formulations may likewise be used as a gluefor fibrous mats to create a resilient foam-like product. Notably,coconut fiber may be bonded together by natural rubber latex into anon-woven mat to provide a cushion or mattress material that issubstantially all-natural in origin. Despite various claims in the priorart of being “all natural,” the cure system and additives to the naturalrubber may contain synthetic chemicals that may create chemicalsensitivities in certain individuals; furthermore, the natural rubberlatex itself may cause allergic reactions in certain individuals due tothe residual protein.

B. Summary

A foam product based on epoxidized vegetable oil is disclosed whereinthe pre-polymer curative is likewise comprised of naturally occurringand naturally derived products of biological origin. The foam productdisclosed is created without the use of additional foaming agent. Thefoamed product may be created with or without the requirement ofwhipping in air into the pre-cured liquid resin. The foam productdisclosed may have a T_(g) near room temperature, thus providing a lossyproduct. Additionally, the foam product may be formulated to have aT_(g) below room temperature to provide a flexible, springy product.Memory foam attributes may be attained by polymers prepared according tothis disclosure. Such polymers are reaction products of the pre-polymercurative as described herein above and epoxidized vegetable oils,reaction mixtures may also contain other natural polymers and modifiednatural polymers as described in further detail below.

In certain embodiments, the foam product may contain a certain fractionof epoxidized natural rubber. Notably, the process that createsepoxidized natural rubber also reduces the free protein that may createallergic reactions in certain individuals. The reduction in allergicresponse for epoxidized natural rubber compared to untreated naturalrubber is greater than 95%.

Disclosed is a castable resin comprising EVO (and/or any suitableepoxidized triglyceride as disclosed above) combined with thepre-polymer curative (as disclosed above in Section 1), and in oneillustrative embodiment ENR that has been solubilized in the EVO.

It has been found that a pre-polymer curative, as disclosed in Section1, can be created that eliminates the risk of porosity when cured withina certain temperature range, but that evolves gas during the curingprocess when conducted within a second higher temperature range.Furthermore, the oligomeric pre-polymer curative may incorporatesubstantially all of the polyfunctional carboxylic acid so that noadditional solvent is required during the curing process. For example,citric acid is not miscible in ESO but they may be made to react witheach other in a suitable solvent. The amount of citric acid may beselected so that the pre-polymer curative is created so thatsubstantially all of the epoxide groups of the ESO in the pre-polymercurative are reacted with carboxylic acid groups of the citric acid.With sufficiently excess citric acid, the pre-polymerization extent maybe limited so that no gel fraction is formed. That is, the targetpre-polymer curative is a low molecular weight (oligomeric) citric-acidcapped ester-product formed by the reaction between carboxylic acidgroups on the citric acid with epoxide groups on the ESO.

Illustrative oligomeric pre-polymer curatives may be created with weightratios of ESO to citric acid in the range of 1.5:1-0.5:1. If too muchESO is added during pre-polymer curative creation, the solution may geland further incorporation of ESO to create the target resin becomesimpossible. Note that on a weight basis, stoichiometric equivalentamounts of epoxide groups on the ESO and carboxylic acid groups on thecitric acid occur at a weight ratio of 100 parts of ESO to about 30parts of citric acid. A ratio of ESO:citric acid above 1.5:1 may build apre-polymer curative with excessive molecular weight (and henceviscosity) which limits its usefulness as a casting resin. If the ratioof ESO:citric acid is below 0.5:1 it has been found that there is somuch excess citric acid that after solvent evaporation, ungrafted citricacid may precipitate out of solution.

In addition to controlling the ratio of ESO to citric acid, according tothe present disclosure it has been found that selective control of theamount of alcohol used as a solvent may also be used to tailor thephysical properties of the resulting elastomeric foam. It has been foundthat the alcohol solvent may itself be incorporated into the elastomerby forming ester linkages with the polyfunctional carboxylic acid thatare reversible and thus gas-evolving when the material is cured at atemperature higher than that required to make a porosity-free product. Amixture of two or more solvents may be used to tailor the amount ofgrafting of an alcohol-containing solvent onto the citric acid-cappedoligomeric pre-polymer curative.

For example, and without restriction or limitation unless otherwiseindicated in the following claims, isopropyl alcohol (IPA) or ethanolmay be used as a component of a solvent system used to miscibilizecitric acid with ESO. IPA or ethanol are capable of forming an esterlinkage via a condensation reaction with citric acid. Since citric acidhas three carboxylic acids, such grafting reduces the averagefunctionality of the citric acid molecules that are reacting with theESO. This is beneficial in creating an oligomeric structure that is morelinear and therefore less highly branched. Acetone may be used as onecomponent of a solvent system used to miscibilize citric acid with ESO,but unlike IPA or ethanol, acetone itself is not capable of beinggrafted onto the citric acid-capped oligomeric pre-polymer curative.Indeed, during creation of the oligomeric pre-polymer curative it hasbeen found that the reactivity of the pre-polymer curative isdetermined, in part, by the ratio of IPA or ethanol to acetone that maybe used to solubilize citric acid with ESO. That is, in reactionmixtures with the similar amounts of citric acid and ESO, a pre-polymercurative created from a solution with a relatively high ratio of IPA orethanol to acetone creates a lower viscosity product than pre-polymercurative created from a solution with a relatively low ratio of IPA orethanol to acetone under similar reaction conditions. Also, the amountof IPA or ethanol grafted on the pre-polymer curative determines theextent to which such IPA or ethanol is evolved when the formulated resinis foamed at a temperature higher than that required to make aporosity-free resin product.

C. Illustrative Methods and Products

Illustrative blends that create resilient memory foams have been createdfrom a combination of inputs that include a pre-polymer curative, aliquid blend of epoxidized natural rubber and epoxidized vegetable oiland may contain unmodified epoxidized vegetable oil.

In a first illustrative embodiment of a foam material, the resilientmemory foam is produced using a pre-polymer curative creation and bydissolving 50 parts of citric acid in 125 parts of warm IPA, acceleratedby mixing (again with reference to FIG. 1). After dissolution of thecitric acid, 50 parts of ESO is added to the stirring solution. Thesolution is preferably mixed and reacted at temperatures of 60° C.-140°C. with optional use of mild vacuum (50-300 Torr). One illustrativebatch was mixed in a jacketed reactor vessel with a jacket temperatureof 120° C. (solution temperatures of approximately 70° C.-85° C.) andthe citric acid grafting onto ESO occurred concurrently with IPAevaporation. At the end of the reaction sequence it was discovered thatroughly 12 parts of IPA was grafted onto the combined 100 parts of ESOand citric acid. Accordingly, temperatures above the boiling point ofIPA and application of vacuum could no longer yield IPA condensate inthe condensing system. Calculations reveal that of the startingcarboxylic acid sites on the citric acid, roughly 31% reacted withepoxide groups on the ESO (assuming all of the epoxides were convertedduring the reaction to ester linkages), roughly 27% of the carboxylicacid sites reacted with IPA to form pendant esters, and roughly 42%remain unreacted and available for crosslinking the resin in asubsequent processing step. However, these calculations are forillustrative purposes only and in no way limit the scope of the presentdisclosure unless otherwise indicated in the following claims.

In a second illustrative embodiment of a foam material, the resilientmemory foam was created via a rubber-containing resin precursor.Epoxidized natural rubber may be included in resin-based formulations atlevels below twenty-five weight percent (25 wt %) and still yield apourable liquid. Creation of the rubber-containing precursor may be donein two-stages without requiring the use of a solvent for rubberdissolution. In the first stage 100 parts of epoxidized natural rubber(ENR-25) are mixed with 50 parts of ESO using rubber mixing techniques(a two-roll mill or internal mixer). This yields a very soft gum thatcannot effectively be further mixed on rubber processing equipment, butwith the application of heat (e.g., 80° C.) additional ESO may be mixedinto the rubber with a Flacktek Speedmixer or alternative low-horsepowerequipment (e.g., a sigma-blade mixer) to create a flowable liquidcontaining 25% ENR-25 and 75% ESO.

A third illustrative embodiment of a foam material may also produce aresilient memory foam-type creation. In this embodiment, the foamableresin is produced via mixing and curing. For this illustrativeembodiment, 40 parts of pre-polymer curative from the first illustrativeembodiment of a foam material was added to 80 parts of rubber-containingresin from the second illustrative embodiment. The resulting combinationwas then mixed with a Flacktek Speedmixer until a homogeneous solutionwas obtained (about 10 minutes of mixing). This resin was cured usingthe following two procedures:

-   1. Resin cured on 200° C. (nominal temperature) hot griddle (PTFE    coated) just like a pancake. The material foamed to a relatively    homogenous article with memory-foam characteristics; specifically,    lossy behavior. A depiction of the resulting material is shown in    FIG. 18.-   2. Resin was vacuum degassed after mixing and placed on the same    200° C. hot griddle. In this instance, porosity was observed over    the heating element (measured temperature 210° C.) but no porosity    was observed over the region of the griddle without the heating    element (measured temperature 180° C.). Depictions of the resulting    materials are shown in FIG. 19.

From these two procedures, it is clear that there may be two sources ofporosity. One source may involve small bubbles of air that areincorporated during mixing. Additional experimentation has shown thatthe presence of ENR-25 in the resin is an important contributor tostabilizing this incorporated air and preventing bubble coalescenceduring the curing stage. The second source of porosity is evolved gas,likely removal of the grafted IPA, at temperatures at or above 200° C.

As previously described, certain catalysts are known in the art to speedup the carboxylic acid addition to epoxide groups and such may be usedin formulating recipes according to the present disclosure withoutlimitation unless otherwise indicated in the following claims.

D. Applications/Additional Illustrative Products

Materials according to this disclosure may be used as flooring, exercisemats, bedding, shoe insoles, shoe outsoles, or sound absorption panelswithout limitation unless otherwise indicated in the following claims.

Materials according to this disclosure may be molded into complexthree-dimensional articles and multi-laminated articles.Three-dimensional articles may also consist of multiple materialformulations arranged at various locations within an article to providefunctionality required for each location.

The resilient memory foam based on vegetable oil may be used inapplications where polyurethane is used today. Such applications mayinclude shoes, seating, flooring, exercise mats, bedding, soundabsorption panels, and the like without limitation unless otherwiseindicated in the following claims. Many of these articles are consumableitems that if made from synthetic polyurethane foams arenon-biodegradable and are non-recyclable. If such items are made fromthe material disclosed herein, they would be biodegradable and thus notcreate a disposal problem.

Although the methods described and disclosed herein may be configured toutilize a curative comprised of a natural materials, the scope of thepresent disclosure, any discrete process step and/or parameterstherefor, and/or any apparatus for use therewith is not so limited andextends to any beneficial and/or advantageous use thereof withoutlimitation unless so indicated in the following claims.

The materials used to construct the apparatuses and/or componentsthereof for a specific process will vary depending on the specificapplication thereof, but it is contemplated that polymers, syntheticmaterials, metals, metal alloys, natural materials, and/or combinationsthereof may be especially useful in some applications. Accordingly, theabove-referenced elements may be constructed of any material known tothose skilled in the art or later developed, which material isappropriate for the specific application of the present disclosurewithout departing from the spirit and scope of the present disclosureunless so indicated in the following claims.

Having described preferred aspects of the various processes,apparatuses, and products made thereby, other features of the presentdisclosure will undoubtedly occur to those versed in the art, as willnumerous modifications and alterations in the embodiments and/or aspectsas illustrated herein, all of which may be achieved without departingfrom the spirit and scope of the present disclosure. Accordingly, themethods and embodiments pictured and described herein are forillustrative purposes only, and the scope of the present disclosureextends to all processes, apparatuses, and/or structures for providingthe various benefits and/or features of the present disclosure unless soindicated in the following claims.

While the chemical process, process steps, components thereof,apparatuses therefor, products made thereby, and impregnated substratesaccording to the present disclosure have been described in connectionwith preferred aspects and specific examples, it is not intended thatthe scope be limited to the particular embodiments and/or aspects setforth, as the embodiments and/or aspects herein are intended in allrespects to be illustrative rather than restrictive. Accordingly, theprocesses and embodiments pictured and described herein are no waylimiting to the scope of the present disclosure unless so stated in thefollowing claims.

Although several figures are drawn to accurate scale, any dimensionsprovided herein are for illustrative purposes only and in no way limitthe scope of the present disclosure unless so indicated in the followingclaims. It should be noted that the welding processes, apparatusesand/or equipment therefor, and/or impregnated and reacted uponsubstrates produced thereby are not limited to the specific embodimentspictured and described herein, but rather the scope of the inventivefeatures according to the present disclosure is defined by the claimsherein. Modifications and alterations from the described embodimentswill occur to those skilled in the art without departure from the spiritand scope of the present disclosure.

Any of the various features, components, functionalities, advantages,aspects, configurations, process steps, process parameters, etc. of achemical process, a process step, a substrate, and/or a impregnated andreacted substrate, may be used alone or in combination with one anotherdepending on the compatibility of the features, components,functionalities, advantages, aspects, configurations, process steps,process parameters, etc. Accordingly, an infinite number of variationsof the present disclosure exist. Modifications and/or substitutions ofone feature, component, functionality, aspect, configuration, processstep, process parameter, etc. for another in no way limit the scope ofthe present disclosure unless so indicated in the following claims.

It is understood that the present disclosure extends to all alternativecombinations of one or more of the individual features mentioned,evident from the text and/or drawings, and/or inherently disclosed. Allof these different combinations constitute various alternative aspectsof the present disclosure and/or components thereof. The embodimentsdescribed herein explain the best modes known for practicing theapparatuses, methods, and/or components disclosed herein and will enableothers skilled in the art to utilize the same. The claims are to beconstrued to include alternative embodiments to the extent permitted bythe prior art.

Unless otherwise expressly stated in the claims, it is in no wayintended that any process or method set forth herein be construed asrequiring that its steps be performed in a specific order. Accordingly,where a method claim does not actually recite an order to be followed byits steps or it is not otherwise specifically stated in the claims ordescriptions that the steps are to be limited to a specific order, it isno way intended that an order be inferred, in any respect. This holdsfor any possible non-express basis for interpretation, including but notlimited to: matters of logic with respect to arrangement of steps oroperational flow; plain meaning derived from grammatical organization orpunctuation; the number or type of embodiments described in thespecification.

What is claimed is:
 1. A thermoset material containing β-hydroxyesterswherein said thermoset material is subject to a mechano-chemical processto regenerate an epoxide and a carboxylic acid functionality.
 2. Thethermoset material according to claim 1 wherein said resin comprises areaction product between an epoxidized triglyceride and a naturallyoccurring polyfunctional carboxylic acid.
 3. The thermoset materialaccording to claim 1 wherein said mechano-chemical process transformsthe thermoset material into a millable gum.
 4. The thermoset materialaccording to claim 1 wherein said regenerated epoxide and carboxylicacid functionality is sufficient to affect a re-crosslinking of saidthermoset material after said mechano-chemical process.
 5. The thermosetmaterial according to claim 1 wherein: a. said thermoset material isadded to an epoxidized natural rubber, and b. said thermoset materialacts as a curative for the epoxidized natural rubber.
 6. The thermosetmaterial according to claim 1 wherein said thermoset material is addedto an epoxidized natural rubber as a sole curative.
 7. The thermosetmaterial according to claim 1 wherein said thermoset materialconstitutes over 20% by weight of an elastomeric content of a rubbercompound.
 8. The thermoset material according to claim 1 wherein saidepoxidized natural rubber constitutes over 20% by weight of anelastomeric content of said thermoset material.
 9. The thermosetmaterial according to claim 1 wherein a power-per-unit-volume of saidthermoset material required to regenerate said epoxide and carboxylicacid functionality is at least 1.9×10⁵ W/l.
 10. The thermoset materialaccording to claim 1 wherein a power-per-unit-volume of said thermosetmaterial required to regenerate said epoxide and carboxylic acidfunctionality is between 1.9×10⁵ W/l and 6.67×10⁵ W/l.
 11. The thermosetmaterial according to claim 9 wherein an average temperature of saidthermoset material during said mechano-chemical process does not exceed75° C.
 12. The thermoset material according to claim 1 wherein thethermoset material is further defined as being a thermoset resin.
 13. Arubber compound containing over 20% by weight of an elastomeric contentof a previously thermoset material, wherein said previously thermosetmaterial is mechano-chemically de-crosslinked during the mixing of therubber compound.
 14. The rubber compound according to claim 13 whereinsaid previously thermoset material consists of a reaction productbetween an epoxidized triglyceride and a naturally occurringpolyfunctional carboxylic acid.
 15. The rubber compound according toclaim 14 wherein said epoxidized triglyceride is selected from a groupconsisting of epoxidized soybean oil, epoxidized linseed oil, epoxidizedcorn oil, epoxidized cottonseed oil, epoxidized canola oil, epoxidizedrapeseed oil, epoxidized grape seed oil, epoxidized poppy seed oil,epoxidized tongue oil, epoxidized sunflower oil, epoxidized saffloweroil, epoxidized wheat germ oil, epoxidized walnut oil, and epoxidizedmicrobial-produced oil.
 16. The rubber compound according to claim 13wherein said naturally occurring polyfunctional carboxylic acid isselected from a group consisting of citric acid, tartaric acid, succinicacid, malic acid, maleic acid, and fumaric acid.
 17. The rubber compoundaccording to claim 13 wherein said mechano-chemical de-crosslinkingregenerates an epoxide and a carboxylic acid functionality in thepreviously thermoset material.
 18. The rubber compound according toclaim 13 wherein an elastomeric content of the compound consists of atleast 20% by weight of an epoxidized natural rubber.
 19. The rubbercompound according to claim 13 wherein: a. the previously thermosetmaterial is mechano-chemically de-crosslinked during a mixing of therubber compound, and b. the mechano-chemically de-crosslinked thermosetmaterial constitutes at least 20% of a total elastomer content of thecompound.
 20. A material comprising: a. an epoxidized natural rubber;and b. a thermoset material reaction product of an epoxidizedtriglyceride and a naturally occurring polyfunctional carboxylic acid.21. The material according to claim 20 wherein the epoxidized naturalrubber and the thermoset material reaction product of an epoxidizedtriglyceride and a naturally occurring polyfunctional carboxylic acidare self-reactive towards each other so that the epoxidized naturalrubber is crosslinked via β-hydroxyesters.
 22. The material according toclaim 20 wherein the material further contains at least 20% by weight ofa self-same material that had previously been cured.
 23. The materialaccording to claim 20 further comprising a filler selected from amongvarious non-petrochemically derived sources that include: cork powder,ground rice hulls, activated carbon, activated charcoal, kaolin clay,metakaolin clay, precipitated silica, talc, mica, corn starch, mineralpigments, cotton, jute, hemp, ramie, sisal, coconut fiber, kapok fiber,silk, or wool.
 24. The material according to claim 20 wherein saidthermoset material is further defined as a thermoset resin.
 25. Amaterial comprising: a. an epoxidized natural rubber cured with areaction product of an epoxidized triglyceride and a naturally occurringpolyfunctional carboxylic acid, and b. wherein said material contains atleast 20% by weight of a remilled elastomer that was a self-sameepoxidized natural rubber cured with a reaction product of an epoxidizedtriglyceride and a naturally occurring polyfunctional carboxylic acid.26. The material according to claim 25 wherein the remilled elastomerconstitutes at least 50% by weight of the material content.
 27. Thematerial according to claim 25 wherein the remilled elastomerconstitutes at least 75% by weight of the material content.
 28. Thematerial according to claim 25 further comprising a filler selected fromamong various non-petrochemically derived sources that include: corkpowder, ground rice hulls, activated carbon, activated charcoal, kaolinclay, metakaolin clay, precipitated silica, talc, mica, corn starch,mineral pigments, cotton, jute, hemp, ramie, sisal, coconut fiber, kapokfiber, silk, or wool.